  <sect1 id="sect-graphs-overview">
    <title>Overview of Graphs</title>

    <para>
      This overview will start with a brief summary of the process
      involved in creating a graph, then will discuss the terminology
      used in this document, will present the components of a graph,
      and present the hierarchy of the components used in to configure
      the graphs.
    </para>

      <sect2 id="sect-graphs-overview-process">
        <title>The Graph Creation Process</title>

	<para> 
	  The process of graph creation involves several steps each of
	  which requires the user to understand clearly what they
	  intend to do. This outline is presented to help users
	  understand the subsequent discussion in this document.
        </para>


      <procedure>
        <title>Outline of the procedure to create a graph.</title>

        <step>
	  <title>
	    Data entry.
	  </title>
	  <para>
	   Before a graph can be created, the data must be entered
	  into a workbook.
	  </para>
	</step>

        <step>
	  <title>
	    (Optional) Data pre-selection.
	  </title>
	  <para>
	    As explained in <xref
	    linkend="sect-graphs-preselect" />, it is possible
	    to pre-select the data and have &gnum; correctly assign
	    the cell contents into series names, category labels and
	    data values. This process can only be understood once the
	    rest of the graph creation process has been mastered so
	    the discussion of pre-selecting data is left until the end
	    of this section.
	  </para>
	</step>

        <step>
	  <title>
	    Opening the graph guru
	  </title>
	  <para>
	    The <interface>Graph Guru</interface> can be opened in two
	    ways. It can be opened by clicking on the <guibutton>Graph
	    Guru</guibutton> button,
	    <inlinemediaobject>
              <imageobject>
                <imagedata fileref="figures/button-graph.png" />
              </imageobject>
              <textobject>
                <phrase>An image of the toolbar graph guru button.</phrase>
              </textobject>
            </inlinemediaobject>, which is on the standard toolbar
	    immediately to the left of the zoom box. Alternatively the
	    <interface>Graph Guru</interface> can be opened by using,
	    in the <guimenu>Insert</guimenu> menu, the
	    <guimenuitem>Chart</guimenuitem> menu item.
	  </para>
	</step>

        <step>
	  <title>
	    Configuring the graph
	  </title>
	  <para>
	    The <interface>Graph Guru</interface> provides the user
	    with a large number of options to configure the graph, its
	    charts and the plots. The first panel provides a way to
	    select the plot type, sub-type and, for some types, a
	    style. The second panel allows the user to configure each
	    element of the graph. When the configuration is complete,
	    the guru is dismissed by clicking the
	    <guibutton>OK</guibutton> button. This step will be
	    explained in detail in <xref
	    linkend="sect-graphs-graphguru-navigating" />,
	    below. 
	  </para>
	</step>

        <step>
	  <title>
	    Inserting the graph
	  </title>
	  <para>
	    Finally, the graph is inserted into
	    the worksheet like any other graphical element, as was
	    explained in <xref
	    linkend="sect-graphical-overview-adding" />. 
	  </para>
	</step>
      </procedure>


    </sect2>




    <sect2 id="sect-graphs-overview-terms">
      <title>On Terminology</title>

  <note>

    <para>
      The terminology used for describing the components of data
      graphs is confusing because graphs use many components and the
      words are applied arbitrarily to each component. For example,
      the words "graph", "chart", and "plot" could be used
      interchangeably but in &gnum;
      these words are used as explained below.
    </para>

    <para>
      The term 'graph' will be used, in this documentation, to refer
      to the entire graphical element placed on the worksheet. A graph
      has an outline and a background, may have one or more titles,
      and will have at least one 'chart'.
    </para>

    <para>
      The term 'chart' will be used to denote an intermediate level
      element which has an outline and a background, may have one or
      more titles, may have a legend and will have at least one
      'plot'. To support the plot, the chart may have a 'grid' area
      behind the plotted data, and have one or more axes.
    </para>

    <para>
      Each 'plot' will be defined to be of a particular type when it
      is created.  Plots will have one or more 'series' of data values
      which will define the magnitude of the values of to be plotted
      and may define a number of other related values including errors
      in the x and y directions.
    </para>

  </note>

  <para>
    This terminology can be used to describe in detail the components
    of a graph in &gnum;. <xref
    linkend="fig-graph-components" /> presents the components of a
    graph. 
  </para>


    </sect2>


    <sect2 id="sect-graphs-overview-components">
      <title>The Components of Graphs</title>

  <figure id="fig-graph-components">
    <title>The components of &gnum; graphs</title>
    <screenshot>
      <mediaobject>
        <imageobject>
          <imagedata fileref="figures/graph-components.png" 
              format="PNG"  />
        </imageobject>
        <textobject>
          <para>
            This screenshot depicts a graph in &gnum; and describes
	    all of the components.
          </para>
        </textobject>
        <caption>
          <para>
	    This screenshot presents several of the major components of
            &gnum; graphs. These components
            will be presented next in their containment hierarchy. The
            hierarchy is used in the <interface>Graph Guru</interface> to
            organize the components so a user can change all the
            preferences.
	  </para>
        </caption>
      </mediaobject>
    </screenshot>
  </figure>


    </sect2>

     <sect2 id="sect-graphs-overview-componentHierarchy">
       <title>The Graph Component Hierarchy</title>

       <para>
         The components that make up a graph in
         &gnum;  are arranged in a
         hierarchy with all the configurable options of the graph
         assigned as properties to one of the components in the
         hierarchy. 
       </para>


  <figure id="fig-graph-componentHierarchy">
    <title>The hierarchy of components and their properties</title>
    <screenshot>
      <mediaobject>
        <imageobject>
          <imagedata fileref="figures/graph-hierarchy.png" 
              format="PNG"  />
        </imageobject>
        <textobject>
          <para>
            This figure includes an image of the graph hierarchy
            presented by the graph guru along with text descriptions
            of each component and of their properties.
          </para>
        </textobject>
        <caption>
          <para>
	    The hierarchy of graph component elements and the associated
            properties. In this case, the element 'X-Axis2' is selected.
	  </para>
        </caption>
      </mediaobject>
    </screenshot>
  </figure>


        <para>
          In &gnum;, Graphs are the top
          level element containing all the other components. Graphs
          have two properties related to the style of the background
          rectangular panel, its fill and its outline. Graphs can hold
          one or more titles and one or more charts.
        </para>

        <para>
          Titles have the same properties related to their background
          rectangular panel, the fill and outline, have
          properties related to the text, the font type, style, and
          size, and have the text data that will be the title itself.
        </para>

	<para>
	  Charts have the same properties related to the background
	  rectangular panel and can contain a number of other
	  components including their own titles, a legend, plot
	  accessories and plots.
        </para>

	<para>
	  Legends have the same properties related to their background
	  rectangular panel and also have the properties related to
	  the font in which the name of each series will be added to
	  the legend, the font type, style, and size.
	</para>

	<para>
	  Certain plot types require accessory components such as the
	  elements related to the creation of a Cartesian coordinate
	  system. Charts which include one or more plots of this kind
	  will have a Grid and may have X (horizontal) and Y
	  (vertical) axes.
	</para>

	<para>
	  Grids are the background of Cartesian plots and have the
	  properties determining the fill of this area and the line
	  pattern displayed behind the plotted series.
	</para>

	<para>
	  Axes have properties related to the outer bounds of the
	  axis, the style of the line drawn for the axis, the font
	  style of the markers along the axis, detail properties of
	  the tics and other markers on the axis, and the number
	  format of the axis markers.

	</para>

	<para>
	  Axis labels share the same properties related to the style
	  of their background rectangular panel, including the fill
	  and outline properties, have properties related to the style
	  of the font used for the text, including the font type,
	  style and size, and the data contents of the text used to
	  label the axis.
	</para>

	<para>
	  The properties of each type of plot, and of the data series
	  they contain, vary depending on the actual type of the
	  plot. For instance, the values of a data series which
	  are  plotted as a pie plot will not have any associated
	  error values, whereas values plotted as columns could be
	  associated to Y-error values and values plotted as an XY
	  scatterplot could be associated with error values in both
	  the X and the Y direction. Obviously, these different plot
	  types will require different options. The options associated
	  with each specific plot type will be discussed below, in 
	  <xref linkend="sect-graphs-elementProperties" />.
	</para>

     </sect2>

   </sect1>





  <sect1 id="sect-graphs-graphguru">
    <title>The Graph Guru</title>

    <para>
      All graphs in &gnum; are created
      using the <interface>Graph Guru</interface> which is a complex
      dialog that allows for detailed customization of each graph.
    </para>



    <sect2 id="sect-graphs-graphguru-components">
      <title>The components of the Graph Guru</title>

      <para>
        The <interface>Graph Guru</interface> consists of two panels
        which appear sequentially. The first panel allows the user to
        select the type of the plot, and possibly a sub-type and a
        style. The second panel provides a way to configure the style
        formats of each component of the final graph. <xref
        linkend="fig-graphguru-panels" /> shows the different areas
        of the two panels of the <interface>Graph Guru</interface>.
      </para>
      
      <figure id="fig-graphguru-panels">
        <title>The two panels of the Graph Guru</title>
	 <screenshot>
          <mediaobject> 
	    <imageobject> 
	      <imagedata fileref="figures/graphguru-components.png"
	                 format="PNG" />
	    </imageobject>
	    <textobject>
	      <para> 
	        This screenshot depicts the two panels of the graph
	        guru.
	      </para>
	    </textobject>
	  </mediaobject>
	</screenshot>
      </figure>

      <para>
        The different parts of each panel of the <interface>Graph
        Guru</interface> have been shaded with boxes of different
        colors and labeled with a letter in <xref
        linkend="fig-graphguru-panels" />. The purpose of each of
        these sections will be explained below:

	<variablelist>
	  <title>The components of the two panels</title>

	  <varlistentry>
	    <term>
	      <guimenu>A</guimenu> - The Plot Type Selection Area

	    </term>
	    <listitem>
	      <para>
	        This area lists the different types of plots which can
		be contained within the graph. The desired plot type
		can be selected simply by placing the mouse cursor
		over the desired type and clicking with the primary
		mouse button. The blue highlight indicates the
		currently selected type. 
	      </para>
	    </listitem>
          </varlistentry>

	  <varlistentry>
	    <term>
	      <guimenu>B</guimenu> - The Preview Area.
	    </term>
	    <listitem>
	      <para>
	        This area shows a preview of the currently selected
		plot type/sub type combination using the default
		settings for this type of plot.
	      </para>
	    </listitem>
          </varlistentry>

	  <varlistentry>
	    <term>
	      <guimenu>C</guimenu> - The Plot Subtype Area.
	    </term>
	    <listitem>
	      <para>
	        This area presents a number of icons which change
	        depending on the plot type that has been
	        selected. Certain icons represent plot sub-types, for
	        example, distinguishing plots with columns that are
	        side by side from plots with stacked columns. Other
	        icons represent different plot styles, for example
	        distinguishing line plots in which each data point is
	        labeled with a graphical symbol from line plots where
	        data points do not have any symbol. The highlight box
	        around one icon 
	        indicates which icon is currently chosen.
	      </para>

	      <para>
	        Hovering the mouse pointer over one of these icons causes 
		a description of the plot type to be shown next to the icon. 
	      </para>
	    </listitem>
          </varlistentry>

	  <varlistentry>
	    <term>
	      <guimenu>D</guimenu> - The First Panel Navigation Buttons
	    </term>
	    <listitem>
	      <para>
	        These buttons enable the user to navigate through the
	        <interface>Graph Guru</interface>.
	      </para>
	      
	      <variablelist>

	        <varlistentry>
		  <term>
		    The <guibutton>Help</guibutton> Button
		  </term>
		  <listitem>
		    <para>
		      The <guibutton>Help</guibutton> button should
		      cause this section of the manual to open.
		    </para>
		  </listitem>
		</varlistentry>

	        <varlistentry>
		  <term>
		    The <guibutton>Cancel</guibutton> Button
		  </term>
		  <listitem>
		    <para>
		      The <guibutton>Cancel</guibutton> button will
		      dismiss the <interface>Graph Guru</interface>
		      and return the user to the
		      &gnum; worksheet.
		    </para>
		  </listitem>
		</varlistentry>

	        <varlistentry>
		  <term>
		    The <guibutton>Forward</guibutton> Button
		  </term>
		  <listitem>
		    <para>
		      The <guibutton>Forward</guibutton> button will
		      dismiss the first panel of the <interface>Graph
		      Guru</interface> and open up the second panel.
		    </para>
		  </listitem>
		</varlistentry>

	        <varlistentry>
		  <term>
		    The <guibutton>Insert</guibutton> Button
		  </term>
		  <listitem>
		    <para>
		      The <guibutton>Insert</guibutton> button will
		      dismiss the <interface>Graph Guru</interface> and
		      allow users to insert the graph, as it is
		      currently defined, into the worksheet. The
		      resulting graph may not include any plots or
		      data but it can be modified subsequently using
		      the context menu's
		      <guimenuitem>Properties</guimenuitem> menu entry.
		    </para>
		  </listitem>
		</varlistentry>

	      </variablelist>


	    </listitem>
          </varlistentry>

	  <varlistentry>
	    <term>
	      <guimenu>E</guimenu> - The hierarchy tree of graph components
	    </term>
	    <listitem>
	      <para>
	        This area allows the user to navigate the hierarchy of
	        graph components. The components are arranged in a
	        tree with nodes indicated by arrowheads. Components
	        can be selected by clicking on the component name with
	        the mouse pointer and nodes can be expanded or
	        collapsed by clicking on the arrowheads. The selection
	        of different components in this area will cause
	        different property options to be displayed in area
	        <guimenu>J</guimenu> since each component in the
	        hierarchy has its own specific properties.
	      </para>

	      <para>
	        Immediately below the hierarchy are buttons that
		allow a user to modify the hierarchy of
	        components by adding components with the
	        <guibutton>Add</guibutton> button or by removing
	        components with the <guibutton>Delete</guibutton>
	        button. The <guibutton>Order</guibutton> allows the
	        user to change the stacking order of charts, moving
	        them up or down, or of data series, moving them toward
	        the front or back.
	      </para>
	    </listitem>
          </varlistentry>


	  <varlistentry>
	    <term>
	      <guimenu>F</guimenu> - The preview area
	    </term>
	    <listitem>
	      <para>
	        This area shows a preview of the graph as it will look
	        if the user clicks on the <guibutton>Insert</guibutton> or 
		<guibutton>Apply</guibutton> at
	        the bottom of the panel, in area <guimenu>H</guimenu>.
	      </para>
	    </listitem>
          </varlistentry>

	  <varlistentry>
	    <term>
	      <guimenu>G</guimenu> - The component properties
	    selection area.
	    </term>
	    <listitem>
	      <para>
	        This area allows the user to change the graph by
	        modifying the properties of the component that is
	        selected (highlighted in blue) in area
	        <guimenu>E</guimenu>. For components which have
	        multiple properties these may be grouped into related
	        sets and placed on different tabs. By clicking on the
	        tabs at the upper left, a user can access the
	        properties in each set.
	      </para>
	    </listitem>
          </varlistentry>

	  <varlistentry>
	    <term>
	      <guimenu>H</guimenu> - The second panel navigation buttons
	    </term>
	    <listitem>
	      <para>
		If the guru is opened to create a new graph the buttons in 
		this are act in the same way as the buttons in
	        the first panel, in area <guimenu>D</guimenu> except
	        that the <guibutton>Forward</guibutton> is now a
	        <guibutton>Back</guibutton> and takes the user back to
	        the first panel.
	      </para>
	      <para>
		If the guru is opened to modify an existing graph the following
		buttons are shown (as in the screenshot 
		<xref linkend="fig-graphguru-panels" />).
	      </para>

	      <variablelist>

	        <varlistentry>
		  <term>
		    The <guibutton>Help</guibutton> Button
		  </term>
		  <listitem>
		    <para>
		      The <guibutton>Help</guibutton> button should
		      cause this section of the manual to open.
		    </para>
		  </listitem>
		</varlistentry>

	        <varlistentry>
		  <term>
		    The <guibutton>Cancel</guibutton> Button
		  </term>
		  <listitem>
		    <para>
		      The <guibutton>Cancel</guibutton> button will
		      dismiss the <interface>Graph Guru</interface>
		      and return the user to the
		      &gnum; worksheet, leaving the graph unchanged.
		    </para>
		  </listitem>
		</varlistentry>

	        <varlistentry>
		  <term>
		    The <guibutton>Apply</guibutton> Button
		  </term>
		  <listitem>
		    <para>
		      The <guibutton>Apply</guibutton> button will
		      dismiss the <interface>Graph Guru</interface> and
		      apply the changes to the current graph.
		    </para>
		  </listitem>
		</varlistentry>

	      </variablelist>

	    </listitem>
          </varlistentry>

	  <varlistentry>
	    <term>
	      <guimenu>K</guimenu> - The panel rearrangement handles
	    </term>
	    <listitem>
	      <para>
	        These triple dots in various places of the two panels of the 
		graph guru indicate that the mouse can be used
	        to change the size of the different areas. These handles can be
	        used by placing the mouse pointer above a handle,
	        clicking and holding with the primary mouse button,
	        then dragging the handle to a new position, and then
	        releasing the mouse button.
	      </para>
	    </listitem>
          </varlistentry>

        </variablelist>

      </para>


    </sect2>

    <sect2 id="sect-graphs-graphguru-navigating">
      <title>Navigating the graph guru</title>

      <para>
        Graphs in &gnum; are created using
        the <interface>Graph Guru</interface>. The process involved in
        using this 'guru' essentially follows the alphabetical labels
        presented in <xref linkend="fig-graphguru-panels" />.
      </para>
      <procedure>
        <title>The Graph Creation Process</title>

        <step>
	  <title>Data Pre-selection</title>
          <para>

	    Advanced users generally start by pre-selecting at least
            some of the data they will use in their plots. However,
            this step requires a complete understanding graphs and
            this step is not described here. <xref
            linkend="sect-graphs-preselect" /> will explain
            data preselection once the rest of the graphing process
            has been explained.
          </para>
        </step>

        <step>
          <title>Launching the Graph Guru</title>
          <para>
            The <interface>Graph guru</interface> can be started in
            two ways. One way to start the <interface>Graph
            Guru</interface> is to click, with the primary mouse
            button, on the toolbar graph button,
            <inlinemediaobject>
              <imageobject>
                <imagedata fileref="figures/button-graph.png" />
              </imageobject>
              <textobject>
                <phrase>
                  The icon on the toolbar button which starts the
                  graph guru.
      	        </phrase>  
              </textobject>
             </inlinemediaobject>. Another way is to select, from the
             <guimenu>Insert</guimenu> menu, the
             <guimenuitem>Chart...</guimenuitem> menu item. Both
             approaches will launch the <interface>Graph Guru</interface>.
          </para>
        </step>

        <step>
          <title>Selecting the plot type, sub-type, and style.</title>

          <para>
            The <interface>Graph guru</interface> opens to the first
            of two panels. The areas of this panel are shown in the
            left hand side of <xref linkend="fig-graphguru-panels"
            />. This panel enables the user to select the type of the
            first plot in the chart, and its sub-type and style. To
            make a graph with multiple plots, a user should start by
            selecting the first plot; subsequent plots can be added
            later. 
          </para>
          
          <procedure>
            <step>
              <title>Picking the plot type</title>
              <para>
                The first area, area <guimenu>A</guimenu>, provides
                a list of the plot types. The user can pick one of
                the types by placing the mouse pointer on top of
                that appropriate entry in the list and clicking the
                primary mouse button. The blue highlight indicates
                which plot type has been chosen. The characteristics
                of the different plot types are explained extensively
                in <xref
                linkend="sect-graphs-overview-types" />. 
              </para>
            </step>
            <step>
              <title>Picking the plot sub-type and style</title>
              <para>
                The second area of the first panel of the
                <interface>Graph Guru</interface>, labeled
                <guimenu>B</guimenu> in <xref
                linkend="fig-graphguru-panels" />, presents one or
                more icons. The icons presented in this area will
                change depending on what plot type is highlighted in
                area <guimenu>A</guimenu>. The icons provide a way
                to select a sub-type of plot, for example, the icons
                for the column plot type provide the choice between
                plotting columns of each data series side-by-side or
                plotting these columns stacked upon each other.
                These icons may also provide a way to quickly select
                different styles for the plot type, for example the
                icons for the line type provide a choice between
                plotting a simple line or placing markers at the
                points along the line. The sub-type cannot be
                changed in the next panel of the <interface>Graph
                Guru</interface> without deleting the plot and
                creating a new one. However, the style choices can
                be altered in the next panel. The meaning of each of
                these icons is explained in <xref
                linkend="sect-graphs-overview-types" />
                below grouped by plot type. If data has been
                pre-selected, clicking on the <guibutton>Show
                Sample</guibutton> will present a preview of the plot
                type in area <guimenu>B</guimenu>.
              </para>
            </step>
            <step>
              <title>Moving to the next panel</title>
              <para>
                Once a plot type has been chosen in area
                <guimenu>A</guimenu> and an icon selected in area
                <guimenu>B</guimenu>, the first panel has been
                completed. Clicking on the
                <guibutton>Forward</guibutton> button will dismiss
                the first panel of the <interface>Graph
                Guru</interface> and bring up the second panel.
              </para>
            </step>
          </procedure>
        </step>

        <step>
          <title>Configuring the plot</title>
          <para>
            The second panel of the <interface>Graph Guru</interface>
            enables users to configure the plot. This includes
            determining the values which will actually be plotted,
            adding titles to various components, labels to the data
            series, names to data categories, and changing the
            appearance of the different components.
          </para>

          <para>
            The simplest way both to learn the hierarchy of components
            in &gnum; graphs and to
            understand the properties which can be changed for each
            component is to work sequentially through all of the
            components while both noting the components which can be
            added, listed in the drop down menu when the
            <guibutton>Add</guibutton> button is pressed, and
            observing the properties of the component which can be
            altered, shown in the lower part of the panel, the area
            labeled <guimenu>J</guimenu> in <xref
            linkend="fig-graphguru-panels" />. Each component in the
            hierarchy can be selected in turn using the complete tree
            of all the components presented in the top leftmost area,
            labeled <guimenu>F</guimenu>. Components can be selected
            by placing the mouse pointer over their name in this tree
            and then clicking with the primary mouse button. The
            currently selected component is indicated by the blue
            highlight on that line. Changing the selected component
            will also change the properties listed in area
            <guimenu>J</guimenu>. Tree nodes, indicated by arrowheads
            in front of the name of a component, can be expanded or
            collapsed with alternative mouse clicks.
          </para>

          <para>
            The second panel of the <interface>Graph Guru</interface>
            only allows two types of actions to be performed: the
            hierarchy of component elements can be modified or the
            properties of an element can be altered.
          
            <variablelist>
              <title></title>


              <varlistentry>
                <term><guimenu>Changing the component elements</guimenu></term>
                <listitem>
                  <para>
      	            The component elements of the graph can be changed
      	            using the buttons in area
      	            <guimenu>G</guimenu>. Elements can be added,
      	            deleted or re-ordered.
      	          </para>

                  <variablelist>
                    <title></title>

                    <varlistentry>
                      <term>Adding component elements</term>
                      <listitem>
                        <para>
      	                  An element can be added by selecting the
      	                  parent element in the hierarchy presented
      	                  in area <guimenu>F</guimenu> and then
      	                  clicking and holding the
      	                  <guibutton>Add</guibutton> button. This action
      	                  will reveal a drop down list including all
      	                  the possible elements that can be added. By
      	                  moving the mouse pointer onto the drop down
      	                  list and releasing the mouse button while
      	                  the pointer is over an element, that
      	                  element will be added. To add a plot to a
      	                  chart, it is necessary to navigate into the
      	                  sub-menu to select the plot type and then
      	                  into that sub-menu to select a plot
      	                  sub-type or style in a process that mimics
      	                  the process of selecting a plot discussed above.
      	                </para>
                      </listitem>
                    </varlistentry>

                    <varlistentry>
                      <term>Deleting component elements</term>
                      <listitem>
                        <para>
      	                  An element can be deleted by selecting the
      	                  element in the hierarchy presented in area
      	                  <guimenu>F</guimenu>, and then clicking the
      	                  <guibutton>Delete</guibutton> button below
      	                  the hierarchy.
      	                </para>
                      </listitem>
                    </varlistentry>

                    <varlistentry>
                      <term>Re-ordering component elements</term>
                      <listitem>
                        <para>
      		          The order of some of the elements can be
      	                  interchanged using the
      	                  <guibutton>Order</guibutton> button below
      	                  the element hierarchy. For example, if an
      	                  element has two titles, the order of the
      	                  titles could be swapped. Similarly the
      	                  vertical order of charts can be
      	                  interchanged. The effect on plots and series
      	                  is different. For those elements, the order
      	                  button changes the stacking order in the
      	                  front to back dimension. For example, if a
      	                  chart has a bar plot and a line plot, the
      	                  order button will change which of the two
      	                  plots is visible in front of the other.
      	                </para>
                      </listitem>
                    </varlistentry>

                  </variablelist>

      	        </listitem>
              </varlistentry>


              <varlistentry>
                <term>
                  <guimenu>Configuring the properties of the Element</guimenu>
                </term>
                <listitem>
                  <para>
      	            The bottom area of the second panel, area
      	            <guimenu>J</guimenu> in <xref
      	            linkend="fig-graphguru-panels"/>, allows the user
      	            to configure the properties of each element in the
      	            hierarchy. When there are many properties, they
      	            will be grouped into similar sets and placed on
      	            different tabs. The detailed explanation of how to
      	            configure each property of each element will be
      	            explained in <xref
      	            linkend="sect-graphs-elementProperties" /> below.
      	          </para>
                </listitem>
              </varlistentry>
            </variablelist>
           
            Once the plot is sufficiently configured, it can be placed
            on the worksheet to assess its appearance. The user can
            return to this panel of the <interface>Graph
            Guru</interface> using the context menu on the graph. The
            <interface>Graph Guru</interface> is dismissed by
            clicking on the <guibutton>OK</guibutton> button.
<!-- TODO: Change when the button label changes from "OK" (HIG) -->
          </para>
        </step>

        <step>
          <title>Place the graph</title>
          <para>
            After exiting the <interface>Graph Guru</interface>, the
            user must place the graph on a worksheet. Immediately
            after exiting the <interface>Graph Guru</interface>, the
            mouse pointer will have changed to the thin cross-hair
            cursor. The user can place the graph by moving the pointer
            over the worksheet and clicking once with the primary
            mouse button. Alternatively, the user can place and size
            the graph by determining two of the corners of the
            graph. This is done by moving the pointer onto the
            worksheet to the first corner, clicking and holding the
            primary mouse button, dragging the mouse pointer to the
            opposite corner and releasing the mouse button. 
          </para>
        </step>

        <step>
          <title>Modifying an existing graph</title>
          <para>
            A graph which has already been created can be modified by
            clicking on the graph with one of the secondary mouse
            buttons in order to invoke the context menu and then
            selecting the <guimenuitem>Properties</guimenuitem> menu
            entry. This will cause the second panel of the
            <interface>Graph Guru</interface> to appear which will
            enable the user to make any desired modifications. The use
            of the context menu was discussed in <xref
            linkend="sect-graphical-overview-contextmenu" />.
          </para>
        </step>

        <step>
          <title>Deleting a graph</title>
          <para>
            A graph which has been made can be deleted by invoking the
            context menu and selecting the
            <guimenuitem>Delete</guimenuitem> menu item. 
          </para>
        </step>

      </procedure>



    </sect2>


  </sect1>









  <sect1 id="sect-graphs-overview-types">
    <title>Plot Types</title>

    <para>
      &gnum; graphs can include any of
      the plot types presented below. The section for each type
      explains the overall concept of the plot, gives an example,
      explains the data required for the plot type, and explains the
      icons in the <interface>Graph Guru</interface> which allow
      setting the plot sub-type and style.
    </para>


    <sect2 id="sect-graphs-overview-types-area" >
      <title>
        Area Plots
      </title>

      <para>
        Area plots present the numeric values of categorical data with
        the data values of each series connected by a line and the
        area below the line shaded. This type is directly analogous to
        the line plot type. Sequential data values are considered to
        belong to different categories and are plotted along the
        horizontal axis at equally spaced intervals. The data
        values from different series are assigned to these categories
        based on the position of the value in the series, for example,
        the second data value taken from each series all share one
        category. The data values are plotted along the vertical (Y)
        axis according to their numeric value and the particular
        sub-type chosen for the area plot.
      </para>

      <para>
        Area plot sub-types provide three options for relating the
        values from different data series. The first sub-type plots
        each series independently with the data value determining the
        vertical distance between each point and the horizontal
        axis. The second sub-type plots the series stacked on each
        other in a cumulative fashion with the data value of each
        series determining the vertical distance from the point to the
        sum of the values in all the previous series. For example, if
        the first series starts with values 
	<literal>{3.9, 4.2, ...}</literal>, the second
        series with values 
        <literal>{1.2, 3.5, ...}</literal>, and the
        third series with values 
	<literal>{3.1, 1.9, ...}</literal>, then the
        point value for the second element of the third series will be
        plotted at 9.6 
	(since <literal>9.6=4.2+3.5+1.9</literal>) along
        the vertical axis. The third sub-type plots each series based
        on the proportional contribution of the value to the total of
        all values in that category. Using the example above, the
        three values would be plotted at 0.4375, 0.8020, and 1 because
        the intervals between zero and each of these numbers is
        <literal>0.4375=4.2/(4.2+3.5+1.9)</literal>
        for the first, 
	<literal>0.3645...=3.5/(4.2+3.5+1.9)</literal> for the
        second, and 
        <literal>0.1979...=1.9/(4.2+3.5+1.9)</literal> 
	for the third, although, by default, these numbers are
        presented as percentages on the vertical (Y) axis.
      </para>


      <para>
        Area plots do not have any pre-defined styles.
      </para>


      <figure id="fig-graph-types-example-area">
        <title>An example of area plots</title>
              <screenshot>
                <mediaobject>
                  <imageobject>
                    <imagedata fileref="figures/graph-example-area.png" 
                               format="PNG"  />
                    </imageobject>
                    <textobject>
                      <para>
		        A screenshot of a worksheet with a data table
                        and a graph containing an area plot.
                      </para>
                    </textobject>
                    <caption>
                      <para>
	                This screenshot shows a table of data and three
                        area plots. The data consist of three series
                        organized by row and starting with the words
                        "Widgets", "Gadgets", and "Lumpets". Each of
                        these series has values in five categories. The
                        three graphs illustrate the three sub-types of
                        area plots, with the series plotted
                        independently in the left plot, stacked in the
                        middle plot, and proportionately stacked in the
                        right plot.
	              </para>
                    </caption>
                  </mediaobject>
                </screenshot>
      </figure>

      <para>
        Each series in area plots can include three main elements and
        two error elements, although only the value element is
        necessary. The series can have a 'Name' element, which is a
        single text entry used to identify the series, must have a
        'Values' element, which is a sequence of numeric values, and
        may have a 'Label' element, which is a sequence of text
        entries used to identify the categories.  All of these
        elements can be defined as references to a region of the
        worksheet, as literally defined entries, or as formula
        expressions which result in the correct type. The 'Label'
        element is shared by all of the series. The legend added to an
        area plot identifies the different series, by default using
        the entries of the 'Name' element of each series. The two
        error elements include a list for errors in the positive
        direction and one for errors in the negative direction.
      </para>

<table frame='all'><title>The data in each area plot series</title>
<tgroup cols='3' align='left' colsep='1' rowsep='1'>

<thead>
<row>
  <entry align="center">Element</entry>
  <entry align="center">Type</entry>
  <entry align="center">Example</entry>
</row>
</thead>
<tbody>
<row>
  <entry>Name</entry>
  <entry>A single textual element labeling the data series. These will
    be used in the legend which may be displayed with the area
    plot.</entry> 
  <entry>{"Widgets"}</entry>
</row>
<row>
  <entry>Value</entry>
  <entry>A series of numeric values.</entry>
  <entry>{1293, 2502, 3297, 1100, 2487}</entry>
</row>
<row>
  <entry>Label</entry>
  <entry>A series of textual elements labeling each
    value. Generally, this series will have as many entries as there
    were in the "Value" series. These entries are shared by all the
    series in the area plot.</entry> 
  <entry>{"North", "South", "Central", "East", "West"}</entry>
</row>
<row>
  <entry>Error (+)</entry>
  <entry>A list of numeric values with as many elements as there
  were in the 'Value' list. These values can be in the same units as
  the numeric values in the 'Value' list, can be proportions or can be
  proportions multiplied by one hundred.</entry> 
  <entry>{0.10, 0.12, 0.09, 0.11, 0.09}</entry>
</row>
<row>
  <entry>Error (-)</entry>
  <entry>A list of numeric values with as many elements as there
  were in the 'Value' list. These values can be in the same units as
  the numeric values in the 'Value' list, can be proportions or can be
  proportions multiplied by one hundred.</entry> 
  <entry>{0.08, 0.11, 0.10, 0.09, 0.11}</entry>
</row>
</tbody>
</tgroup>
</table>

      <para>
        Area plots provide three icons to choose one of the three
      area plot sub-types.
      </para>



      <variablelist>
        <title>Area plot sub-type and style options.</title>
	      <varlistentry>
	        <term>
		    <inlinemediaobject>
                      <imageobject>
                        <imagedata fileref="figures/chart_area_1_1.png" />
                      </imageobject>
                      <textobject>
                        <phrase>
		          The icon for an area plot of the sub-type with
	                  independent, overlapping areas.
	                </phrase>
                      </textobject>
                    </inlinemediaobject>
	        </term>
	        <listitem>
	          <para>
		    The icon for an area plot of the sub-type with independent,
	            overlapping areas.
		  </para>
		</listitem>
	      </varlistentry>

	      <varlistentry>
	        <term>
		    <inlinemediaobject>
                      <imageobject>
                        <imagedata fileref="figures/chart_area_1_2.png" />
                      </imageobject>
                      <textobject>
                        <phrase>
		          The icon for an area plot of the sub-type with
                      stacked areas.
	                </phrase>
                      </textobject>
                    </inlinemediaobject>
	        </term>
	        <listitem>
	          <para>
		    The icon for an area plot of the sub-type with
                    stacked areas.
		  </para>
		</listitem>
	      </varlistentry>
	      <varlistentry>
	        <term>
		    <inlinemediaobject>
                      <imageobject>
                        <imagedata fileref="figures/chart_area_1_3.png" />
                      </imageobject>
                      <textobject>
                        <phrase>
		          The icon for an area plot of the sub-type with
                          stacked, proportionate areas.
	                </phrase>
                      </textobject>
                    </inlinemediaobject>
	        </term>
	        <listitem>
	          <para>
		    The icon for an area plot of the sub-type with
                    stacked, proportionate areas.
		  </para>
		</listitem>
	      </varlistentry>


	    </variablelist>


    </sect2>

    <sect2 id="sect-graphs-overview-types-bar" >
      <title>
        Bar Plots
      </title>

      <para>
        Bar plots present the numeric values of categorical data with
        the data values of each series represented as a horizontal
        bar. Sequential data values are considered to belong to
        different categories and are plotted along the vertical
        axis at equally spaced intervals. The data values from
        different series are assigned to these categories based on the
        position of the value in the series, for example, the second
        data value taken from each series all share one category. The
        data values are plotted along the horizontal (X) axis as bars
        of different lengths and positions depending on the numeric
        content of the data value and the particular sub-type
        chosen for the bar plot.
      </para>

      <para>
        Bar plot sub-types provide three options for relating the
        values from different data series. The first sub-type plots
        each series independently in adjacent bars, each of which is
        tied to the vertical axis and has its length determined by the
        numeric content of the data value. The second sub-type plots
        each series as a horizontally stacked set of bars with the
        horizontal length of each element determined by the numeric
        content of the data value and the position of the bar
        determined by the position of the element in the data
        series. For example, if the first series starts with values
	<literal>{3.9, 4.2, ...}</literal>, the second
        series with values 
        <literal>{1.2, 3.5, ...}</literal>, and the
        third series with values 
	<literal>{3.1, 1.9, ...}</literal>, then the third bar will be
        plotted ranging from 7.7 to 9.6, since 
	<literal>7.7=4.2+3.5</literal> and 
	<literal>9.6=4.2+3.5+1.9</literal>. The third sub-type plots
        each series as a horizontally stacked set of bars scaled to
        the total all the numeric values in that category. Using the
        example above, the three bars would range from 0 to 0.4375,
        from 0.4375 to 0.8020, and from 0.8020 to 1 respectively
        because the intervals are the proportional contribution of
        each data value to the total, i.e.
        <literal>0.4375=4.2/(4.2+3.5+1.9)</literal>
        for the first, 
	<literal>0.3645...=3.5/(4.2+3.5+1.9)</literal> for the
        second, and 
        <literal>0.1979...=1.9/(4.2+3.5+1.9)</literal> 
	for the third. By default, these numbers are
        presented as percentages on the horizontal (X) axis.
      </para>

      <para>
        Bar plots do not have any pre-defined styles.
      </para>



      <figure id="fig-graph-types-example-bar">
        <title>An example of bar plots</title>
              <screenshot>
                <mediaobject>
                  <imageobject>
                    <imagedata fileref="figures/graph-example-bar.png" 
                               format="PNG"  />
                    </imageobject>
                    <textobject>
                      <para>
		        A screenshot of a table of data and three bar
                        plots made using those data. 
                      </para>
                    </textobject>
                    <caption>
                      <para>
	                This screenshot shows a table of data and three
                        bar plots. The data consist of three series
                        organized by row and starting with the words
                        "Widgets", "Gadgets", and "Lumpets". Each of
                        these series has values in five categories. The
                        three graphs illustrate the three sub-types of
                        bar plots, with the series plotted
                        independently in the left plot, stacked in the
                        middle plot, and proportionately stacked in the
                        right plot.
	              </para>
                    </caption>
                  </mediaobject>
                </screenshot>
      </figure>

      <para>
        Each series in bar plots can include three main elements and
        two error elements, although only the value element is
        necessary. The series can have a 'Name' element, which is a
        single text entry used to identify the series, must have a
        'Values' element, which is a sequence of numeric values, and
        may have a 'Label' element, which is a sequence of text
        entries used to identify the categories.  All of these
        elements can be defined as references to a region of the
        worksheet, as literally defined entries, or as formula
        expressions which result in the correct type. The 'Label'
        element is shared by all of the series. The legend added to a
        bar plot identifies the different series, by default using the
        entries of the 'Name' element of each series. The two error
        elements include a list for errors in the positive direction
        and one for errors in the negative direction.
      </para>

<table frame='all'><title>The data in each bar plot series</title>
<tgroup cols='3' align='left' colsep='1' rowsep='1'>

<thead>
<row>
  <entry align="center">Element</entry>
  <entry align="center">Type</entry>
  <entry align="center">Example</entry>
</row>
</thead>
<tbody>
<row>
  <entry>Name</entry>
  <entry>A single textual element labeling the data series. These will
    be used in the legend which may be displayed with the bar
    plot.</entry>
  <entry>{"Widgets"}</entry>
</row>
<row>
  <entry>Value</entry>
  <entry>A series of numeric values.</entry>
  <entry>{1293, 2502, 3297, 1100, 2487}</entry>
</row>
<row>
  <entry>Label</entry>
  <entry>A series of textual elements labeling each
  value. Generally, this series will have as many entries as there
  were in the "Value" series. These entries are shared by all the
    series in the bar plot.</entry> 
  <entry>{"North", "South", "Central", "East", "West"}</entry>
</row>
<row>
  <entry>Error (+)</entry>
  <entry>A list of numeric values with as many elements as there
  were in the 'Value' list. These values can be in the same units as
  the numeric values in the 'Value' list, can be proportions or can be
  proportions multiplied by one hundred.</entry> 
  <entry>{0.10, 0.12, 0.09, 0.11, 0.09}</entry>
</row>
<row>
  <entry>Error (-)</entry>
  <entry>A list of numeric values with as many elements as there
  were in the 'Value' list. These values can be in the same units as
  the numeric values in the 'Value' list, can be proportions or can be
  proportions multiplied by one hundred.</entry> 
  <entry>{0.08, 0.11, 0.10, 0.09, 0.11}</entry>
</row>
</tbody>
</tgroup>
</table>

      <para>
        Bar plots provide three icons to choose one of the three bar
      plot sub-types.
      </para>



      <variablelist>
        <title>Bar plot sub-type and style options.</title>

	      <varlistentry>
	        <term>
		    <inlinemediaobject>
                      <imageobject>
                        <imagedata fileref="figures/chart_bar_1_1.png" />
                      </imageobject>
                      <textobject>
                        <phrase>
		          The icon for a bar plot of the sub-type with
                          independent, adjacent bars.
	                </phrase>
                      </textobject>
                    </inlinemediaobject>
	        </term>
	        <listitem>
	          <para>
		    The icon for a bar plot of the sub-type with
                    independent, adjacent bars.
		  </para>
		</listitem>
	      </varlistentry>

	      <varlistentry>
	        <term>
		    <inlinemediaobject>
                      <imageobject>
                        <imagedata fileref="figures/chart_bar_1_2.png" />
                      </imageobject>
                      <textobject>
                        <phrase>
		          The icon for a bar plot of the sub-type with
                          horizontally stacked bars.
	                </phrase>
                      </textobject>
                    </inlinemediaobject>
	        </term>
	        <listitem>
	          <para>
		    The icon for a bar plot of the sub-type with
                    horizontally stacked bars.
		  </para>
		</listitem>
	      </varlistentry>

	      <varlistentry>
	        <term>
		    <inlinemediaobject>
                      <imageobject>
                        <imagedata fileref="figures/chart_bar_1_3.png" />
                      </imageobject>
                      <textobject>
                        <phrase>
		          The icon for a bar plot of the sub-type with
                          horizontally stacked, proportionately scaled bars.
	                </phrase>
                      </textobject>
                    </inlinemediaobject>
	        </term>
	        <listitem>
	          <para>
		    The icon for a bar plot of the sub-type with
                    horizontally stacked, proportionately scaled bars.
		  </para>
		</listitem>
	      </varlistentry>

	    </variablelist>


    </sect2>




    <sect2 id="sect-graphs-overview-types-bubble" >
      <title>
        Bubble Plots
      </title>

      <para>
        The data values from three series of equal length are plotted
	on the Cartesian (X-Y) plane, the value from the first series
	determining the position of the plotted symbol center along
	the X axis, the value from the second series determining the
	position of the plotted symbol center along the Y axis, and
	the value of the third series determining the radius of the
	circle plotted. Each triplet of series can be plotted with
	different symbols but the data values of any series can be
	shared.
      </para>

      <figure id="fig-graph-types-example-bubble">
        <title>An example of a bubble plot</title>
              <screenshot>
                <mediaobject>
                  <imageobject>
                    <imagedata fileref="figures/graph-example-bubble.png" 
                               format="PNG"  />
                    </imageobject>
                    <textobject>
                      <para>
		        A screenshot of a worksheet with two series of
                        data, each with three lists, and of the
                        resulting bubble plot.
                      </para>
                    </textobject>
                    <caption>
                      <para>
	                This screenshot shows a worksheet with a table
                        of data with two series, each with three lists
                        of numeric values. The screenshot also shows a
                        bubble plot made from these two series.
	              </para>
                    </caption>
                  </mediaobject>
                </screenshot>
      </figure>

      <para>
        Each series in a bubble plot can include four main components
        and four optional error components. The series may have a
        name, a single text value which will identify the series in
        the graph guru and in any legend attached to the chart. The
        series must have two lists of quantitative values, a list of X
        values and a list of Y values, which must have an equal number
        of elements. The series must also have a list, with the same
        number of elements, whose values will determine the size of
        the circles drawn at each point. The series may have lists of
        error components for the X values or the Y values and for
        positive or negative errors.
      </para>

<table frame='all'><title>The data in each bubble series</title>
<tgroup cols='3' align='left' colsep='1' rowsep='1'>

<thead>
<row>
  <entry align="center">Element</entry>
  <entry align="center">Type</entry>
  <entry align="center">Example</entry>
</row>
</thead>
<tbody>
<row>
  <entry>Name</entry>
  <entry>A single textual element labeling the data series.</entry>
  <entry>{"Series1"}</entry>
</row>
<row>
  <entry>X</entry>
  <entry>A list of numeric values, which will place the values along
  the horizontal axis.</entry>
  <entry>{14.5, 2.8, 11.8, 5.7, 8.2}</entry>
</row>
<row>
  <entry>Y</entry>
  <entry>A second list of numeric values, which will place the values along
  the vertical axis.</entry>
  <entry>{154, 29, 63, 90, 107}</entry>
</row>
<row>
  <entry>Bubble</entry>
  <entry>A series of numeric values, which will determine the size of
  each circle drawn at the points.</entry>
  <entry>{45, 54, 34, 23, 37}</entry>
</row>
<row>
  <entry>X Error (+)</entry>
  <entry>A list of numeric values with as many elements as there
  were in the 'X' list. These values can be in the same units as
  the numeric values in the 'X' list, can be proportions or can be
  proportions multiplied by one hundred.</entry> 
  <entry>{0.10, 0.12, 0.09, 0.11, 0.09}</entry>
</row>
<row>
  <entry>X Error (-)</entry>
  <entry>A list of numeric values with as many elements as there
  were in the 'X' list. These values can be in the same units as
  the numeric values in the 'Value' list, can be proportions or can be
  proportions multiplied by one hundred.</entry> 
  <entry>{0.08, 0.11, 0.10, 0.09, 0.11}</entry>
</row>
<row>
  <entry>Y Error (+)</entry>
  <entry>A list of numeric values with as many elements as there were
  in the 'Y' list, and therefore in the 'X' list. These values can be
  in the same units as the numeric values in the 'Y' list, can be
  proportions or can be proportions multiplied by one hundred.</entry>
  <entry>{0.09, 0.11, 0.10, 0.12, 0.09}</entry>
</row>
<row>
  <entry>Y Error (-)</entry>
  <entry>A list of numeric values with as many elements as there were
  in the 'Y' list, and therefore in the 'X' list. These values can be
  in the same units as the numeric values in the 'Y' list, can be
  proportions or can be proportions multiplied by one hundred.
</entry> 
  <entry>{0.10, 0.09, 0.08, 0.11, 0.11}</entry>
</row>
</tbody>
</tgroup>
</table>

      <para>
        Bubble plots have a single icon for the plot style.
      </para>



      <variablelist>
        <title>The icon for bubble plots</title>

	      <varlistentry>
	        <term>
		    <inlinemediaobject>
                      <imageobject>
                        <imagedata fileref="figures/chart_bubble_1_1.png" />
                      </imageobject>
                      <textobject>
                        <phrase>
		          The icon for a bubble plot.
	                </phrase>
                      </textobject>
                    </inlinemediaobject>
	        </term>
	        <listitem>
	          <para>
		    The icon for a bubble plot.
		  </para>
		</listitem>
	      </varlistentry>

      </variablelist>


    </sect2>

    <sect2 id="sect-graphs-overview-types-coloredxy" >
      <title>
        Colored XY Plots
      </title>
        <para>Work in Progress</para>
    </sect2>



    <sect2 id="sect-graphs-overview-types-column" >
      <title>
        Column Plots
      </title>


      <para>
        Column plots present the numeric values of categorical data with
        the data values of each series represented as a vertical
        column. Sequential data values are considered to belong to
        different categories and are plotted along the horizontal
        axis at equally spaced intervals. The data values from
        different series are assigned to these categories based on the
        position of the value in the series, for example, the second
        data value taken from each series all share one category. The
        data values are plotted along the vertical (Y) axis as columns
        of different heights and positions depending on the numeric
        content of the data value and the particular sub-type
        chosen for the column plot.
      </para>

      <para>
        Column plot sub-types provide three options for relating the
        values from different data series. The first sub-type plots
        each series independently in adjacent bars, each of which is
        tied to the horizontal axis and has its height determined by
        the numeric content of the data value. The second sub-type
        plots each series as a vertically stacked set of columns with
        the vertical height of each element determined by the
        numeric content of the data value and the position of the column
        determined by the position of the element in the data
        series. For example, if the first series starts with values
	<literal>{3.9, 4.2, ...}</literal>, the second
        series with values 
        <literal>{1.2, 3.5, ...}</literal>, and the
        third series with values 
	<literal>{3.1, 1.9, ...}</literal>, then the third column will be
        plotted ranging from 7.7 to 9.6, since 
	<literal>7.7=4.2+3.5</literal> and 
	<literal>9.6=4.2+3.5+1.9</literal>. The third sub-type plots
        each series as a vertically stacked set of columns scaled to
        the total all the numeric values in that category. Using the
        example above, the three columns would range from 0 to 0.4375,
        from 0.4375 to 0.8020, and from 0.8020 to 1 respectively
        because the intervals are the proportional contribution of
        each data value to the total, i.e.
        <literal>0.4375=4.2/(4.2+3.5+1.9)</literal>
        for the first, 
	<literal>0.3645...=3.5/(4.2+3.5+1.9)</literal> for the
        second, and 
        <literal>0.1979...=1.9/(4.2+3.5+1.9)</literal> 
	for the third. By default, these numbers are
        presented as percentages on the vertical (Y) axis.
      </para>

      <para>
        Column plots do not have any pre-defined styles.
      </para>


      <figure id="fig-graph-types-example-column">
        <title>An example of column plots</title>
              <screenshot>
                <mediaobject>
                  <imageobject>
                    <imagedata fileref="figures/graph-example-column.png" 
                               format="PNG"  />
                    </imageobject>
                    <textobject>
                      <para>
		        A screenshot of a table of data and three column
                        plots made using those data. 
                      </para>
                    </textobject>
                    <caption>
                      <para>
	                This screenshot shows a table of data and three
                        column plots. The data consist of three series
                        organized by row and starting with the words
                        "Widgets", "Gadgets", and "Lumpets". Each of
                        these series has values in five categories. The
                        three graphs illustrate the three sub-types of
                        column plots, with the series plotted
                        independently in the left plot, stacked in the
                        middle plot, and proportionately stacked in the
                        right plot.
	              </para>
                    </caption>
                  </mediaobject>
                </screenshot>
      </figure>

      <para>
        Each series in column plots can include three main elements
        and two error elements, although only the value element is
        necessary. The series can have a 'Name' element, which is a
        single text entry used to identify the series, must have a
        'Values' element, which is a sequence of numeric values, and
        may have a 'Label' element, which is a sequence of text
        entries used to identify the categories.  All of these
        elements can be defined as references to a region of the
        worksheet, as literally defined entries, or as formula
        expressions which result in the correct type. The 'Label'
        element is shared by all of the series. The legend added to a
        column plot identifies the different series, by default using
        the entries of the 'Name' element of each series. The two
        error elements include a list for errors in the positive
        direction and one for errors in the negative direction.
      </para>

<table frame='all'><title>The data in each column plot series</title>
<tgroup cols='3' align='left' colsep='1' rowsep='1'>

<thead>
<row>
  <entry align="center">Element</entry>
  <entry align="center">Type</entry>
  <entry align="center">Example</entry>
</row>
</thead>
<tbody>
<row>
  <entry>Name</entry>
  <entry>A single textual element labeling the data series. These will
    be used in the legend which may be displayed with the column
    plot.</entry>
  <entry>{"Widgets"}</entry>
</row>
<row>
  <entry>Value</entry>
  <entry>A series of numeric values.</entry>
  <entry>{1293, 2502, 3297, ,1100, 2487}</entry>
</row>
<row>
  <entry>Label</entry>
  <entry>A series of textual elements labeling each
    value. Generally, this series will have as many entries as there
    were in the "Value" series. These entries are shared by all the
    series in the column plot.</entry> 
  <entry>{"North", "South", "Central", "East", "West"}</entry>
</row>
<row>
  <entry>Error (+)</entry>
  <entry>A list of numeric values with as many elements as there
  were in the 'Value' list. These values can be in the same units as
  the numeric values in the 'Value' list, can be proportions or can be
  proportions multiplied by one hundred.</entry> 
  <entry>{0.10, 0.12, 0.09, 0.11, 0.09}</entry>
</row>
<row>
  <entry>Error (-)</entry>
  <entry>A list of numeric values with as many elements as there
  were in the 'Value' list. These values can be in the same units as
  the numeric values in the 'Value' list, can be proportions or can be
  proportions multiplied by one hundred.</entry> 
  <entry>{0.08, 0.11, 0.10, 0.09, 0.11}</entry>
</row>
</tbody>
</tgroup>
</table>

      <para>
        Column plots provide three icons to choose between three plot
        sub-types. 
      </para>



      <variablelist>
        <title>Column plot sub-type and style options.</title>

	      <varlistentry>
	        <term>
		    <inlinemediaobject>
                      <imageobject>
                        <imagedata fileref="figures/chart_column_1_1.png" />
                      </imageobject>
                      <textobject>
                        <phrase>
		          The icon for pie plot of style with joint slices.
	                </phrase>
                      </textobject>
                    </inlinemediaobject>
	        </term>
	        <listitem>
	          <para>
		    The icon for pie plot of style with joint slices.
		  </para>
		</listitem>
	      </varlistentry>

	      <varlistentry>
	        <term>
		    <inlinemediaobject>
                      <imageobject>
                        <imagedata fileref="figures/chart_column_1_2.png" />
                      </imageobject>
                      <textobject>
                        <phrase>
		          The icon for pie plot of style with joint slices.
	                </phrase>
                      </textobject>
                    </inlinemediaobject>
	        </term>
	        <listitem>
	          <para>
		    The icon for pie plot of style with joint slices.
		  </para>
		</listitem>
	      </varlistentry>

	      <varlistentry>
	        <term>
		    <inlinemediaobject>
                      <imageobject>
                        <imagedata fileref="figures/chart_column_1_3.png" />
                      </imageobject>
                      <textobject>
                        <phrase>
		          The icon for pie plot of style with joint slices.
	                </phrase>
                      </textobject>
                    </inlinemediaobject>
	        </term>
	        <listitem>
	          <para>
		    The icon for pie plot of style with joint slices.
		  </para>
		</listitem>
	      </varlistentry>

	    </variablelist>
    </sect2>


    <sect2 id="sect-graphs-overview-types-contour" >
      <title>
        Contour Plots
      </title>
        <para>Work in Progress</para>
    </sect2>


    <sect2 id="sect-graphs-overview-types-dropbar" >
      <title>
        DropBar Plots
      </title>
        <para>Work in Progress</para>
    </sect2>


    <sect2 id="sect-graphs-overview-types-line" >
      <title>
        Line Plots
      </title>

      <para>
        Line plots present the numeric values of categorical data with
        the data values of each series connected by a line. Sequential
        data values are considered to belong to different categories
        and are plotted along the horizontal (X) axis at equally
        spaced intervals. The data values from different series are
        assigned to these categories based on the position of the
        value in the series, for example, the second data value taken
        from each series all share one category. The data values are
        plotted along the vertical (Y) axis according to their numeric
        value and the particular sub-type chosen for the line plot.
      </para>

      <para>
        Line plot sub-types provide three options for relating the
        values from different data series. The first sub-type plots
        each series independently with the data value determining the
        vertical distance between each point and the horizontal
        axis. The second sub-type plots the series stacked on each
        other in a cumulative fashion with the data value of each
        series determining the vertical distance from the point to the
        sum of the values in all the previous series. For example, if
        the first series starts with values 
	<literal>{3.9, 4.2, ...}</literal>, the second
        series with values 
        <literal>{1.2, 3.5, ...}</literal>, and the
        third series with values 
	<literal>{3.1, 1.9, ...}</literal>, then the
        point value for the second element of the third series will be
        plotted at 9.6 
	(<literal>9.6=4.2+3.5+1.9</literal>) along
        the vertical axis. The third sub-type plots each series based
        on the proportional contribution of the value to the total of
        all values in that category. Using the example above, the
        three values would be plotted at 0.4375, 0.8020, and 1 because
        the intervals between zero and each of these numbers is
        <literal>0.4375=4.2/(4.2+3.5+1.9)</literal>
        for the first, 
	<literal>0.3645...=3.5/(4.2+3.5+1.9)</literal> for the
        second, and 
        <literal>0.1979...=1.9/(4.2+3.5+1.9)</literal> 
	for the third, although, by default, these numbers are
        presented as percentages on the vertical (Y) axis.
      </para>

      <para>
        Two styles are available by default for line plots. In the
        first no markers are placed on the value of the point whereas
        in the second a point marker is added wherever the points are
        plotted.
      </para>

      <figure id="fig-graph-types-example-line">
        <title>An example of line plots</title>
              <screenshot>
                <mediaobject>
                  <imageobject>
                    <imagedata fileref="figures/graph-example-line.png" 
                               format="PNG" />
                    </imageobject>
                    <textobject>
                      <para>
		        A screenshot of a line plot and the data
                        necessary to generate the plot.
                      </para>
                    </textobject>
                    <caption>
                      <para>
	                This screenshot shows a table of data and three
                        line plots. The data consist of three series
                        organized by row and starting with the words
                        "Widgets", "Gadgets", and "Lumpets". Each of
                        these series has values in five categories. The
                        three graphs illustrate the three sub-types of
                        line plots, with the series plotted
                        independently in the left plot, stacked in the
                        middle plot, and proportionately stacked in the
                        right plot.
	              </para>
                    </caption>
                  </mediaobject>
                </screenshot>
      </figure>

      <para>
        Each series in line plots can include three main elements and
        two error elements, although only the value element is
        necessary. The series can have a 'Name' element, which is a
        single text entry used to identify the series, must have a
        'Values' element, which is a sequence of numeric values, and
        may have a 'Label' element, which is a sequence of text
        entries used to identify the categories.  All of these
        elements can be defined as references to a region of the
        worksheet, as literally defined entries, or as formula
        expressions which result in the correct type. The 'Label'
        element is shared by all of the series. The legend added to a
        line plot identifies the different series, by default using
        the entries of the 'Name' element of each series. The two
        error elements include a list for errors in the positive
        direction and one for errors in the negative direction.
      </para>

<table frame='all'><title>The data in each line plot series</title>
<tgroup cols='3' align='left' colsep='1' rowsep='1'>

<thead>
<row>
  <entry align="center">Element</entry>
  <entry align="center">Type</entry>
  <entry align="center">Example</entry>
</row>
</thead>
<tbody>
<row>
  <entry>Name</entry>
  <entry>A single textual entry labeling the data series. These will
    be used in the legend which may be displayed with the line
    plot.</entry> 
  <entry>{"Widgets"}</entry>
</row>
<row>
  <entry>Value</entry>
  <entry>A list of numeric values.</entry>
  <entry>{1293, 2502, 3297, 1100, 2487}</entry>
</row>
<row>
  <entry>Label</entry>
  <entry>A list of textual entries labeling each
    value. Generally, this series will have as many entries as there
    were in the 'Value' series. These entries are shared by all the
    series in the line plot.</entry> 
  <entry>{"North", "South", "Central", "East", "West"}</entry>
</row>
<row>
  <entry>Error (+)</entry>
  <entry>A list of numeric values with as many elements as there
  were in the 'Value' list. These values can be in the same units as
  the numeric values in the 'Value' list, can be proportions or can be
  proportions multiplied by one hundred.</entry> 
  <entry>{0.10, 0.12, 0.09, 0.11, 0.09}</entry>
</row>
<row>
  <entry>Error (-)</entry>
  <entry>A list of numeric values with as many elements as there
  were in the 'Value' list. These values can be in the same units as
  the numeric values in the 'Value' list, can be proportions or can be
  proportions multiplied by one hundred.</entry> 
  <entry>{0.08, 0.11, 0.10, 0.09, 0.11}</entry>
</row>
</tbody>
</tgroup>
</table>

      <para>
        Line plots provide six icons to choose between three plot
        sub-types each with two different styles.
      </para>



      <variablelist>
        <title>Line plot sub-type and style options.</title>

	      <varlistentry>
	        <term>
		    <inlinemediaobject>
                      <imageobject>
                        <imagedata fileref="figures/chart_line_1_1.png" />
                      </imageobject>
                      <textobject>
                        <phrase>
		          The icon for a line plot of the sub-type with
                          independent, overlapping
	                  lines and of the style without point markers.
	                </phrase>
                      </textobject>
                    </inlinemediaobject>
	        </term>
	        <listitem>
	          <para>
		    The icon for a line plot of the sub-type with
                    independent, overlapping
	            lines and of the style without point markers.
		  </para>
		</listitem>
	      </varlistentry>

	      <varlistentry>
	        <term>
		    <inlinemediaobject>
                      <imageobject>
                        <imagedata fileref="figures/chart_line_1_2.png" />
                      </imageobject>
                      <textobject>
                        <phrase>
		          The icon for a line plot of the sub-type with stacked
	                  lines and of the style without point markers.
	                </phrase>
                      </textobject>
                    </inlinemediaobject>
	        </term>
	        <listitem>
	          <para>
		    The icon for a line plot of the sub-type with stacked
	            lines and of the style without point markers.
		  </para>
		</listitem>
	      </varlistentry>

	      <varlistentry>
	        <term>
		    <inlinemediaobject>
                      <imageobject>
                        <imagedata fileref="figures/chart_line_1_3.png" />
                      </imageobject>
                      <textobject>
                        <phrase>
		          The icon for a line plot of the sub-type with
                          stacked proportion lines and of the style
                          without point markers.
	                </phrase>
                      </textobject>
                    </inlinemediaobject>
	        </term>
	        <listitem>
	          <para>
		    The icon for a line plot of the sub-type with stacked
                    proportion lines and of the style without point
                    markers.
		  </para>
		</listitem>
	      </varlistentry>

	      <varlistentry>
	        <term>
		    <inlinemediaobject>
                      <imageobject>
                        <imagedata fileref="figures/chart_line_2_1.png" />
                      </imageobject>
                      <textobject>
                        <phrase>
		          The icon for a line plot of the sub-type
                          with overlapping 
	                  lines and of the style with point markers.
	                </phrase>
                      </textobject>
                    </inlinemediaobject>
	        </term>
	        <listitem>
	          <para>
		    The icon for a line plot of the sub-type with overlapping
	            lines and of the style with point markers.
		  </para>
		</listitem>
	      </varlistentry>

	      <varlistentry>
	        <term>
		    <inlinemediaobject>
                      <imageobject>
                        <imagedata fileref="figures/chart_line_2_2.png" />
                      </imageobject>
                      <textobject>
                        <phrase>
		          The icon for a line plot of the sub-type with stacked
	                  lines and of the style with point markers.
	                </phrase>
                      </textobject>
                    </inlinemediaobject>
	        </term>
	        <listitem>
	          <para>
		    The icon for a line plot of the sub-type with stacked
	            lines and of the style with point markers.
		  </para>
		</listitem>
	      </varlistentry>

	      <varlistentry>
	        <term>
		    <inlinemediaobject>
                      <imageobject>
                        <imagedata fileref="figures/chart_line_2_3.png" />
                      </imageobject>
                      <textobject>
                        <phrase>
		          The icon for a line plot of the sub-type with
                          stacked proportion lines and of the style
                          without point markers.
	                </phrase>
                      </textobject>
                    </inlinemediaobject>
	        </term>
	        <listitem>
	          <para>
		    The icon for a line plot of the sub-type with stacked
                    proportion lines and of the style without point
                    markers.
		  </para>
		</listitem>
	      </varlistentry>
	    </variablelist>


    </sect2>

    <sect2 id="sect-graphs-overview-types-minmax" >
      <title>
        Min-Max Plots
      </title>
        <para>Work in Progress</para>
    </sect2>



    <sect2 id="sect-graphs-overview-types-pie" >
      <title>
        Pie Plots
      </title>

      <para>
        Pie plots present the numeric values from a single series of
        categorical data as slices of a circular area, the angular
        arc of each slice determined by the proportional magnitude of
        each value compared to the overall sum of all the values. For
        example, if the series had values { 1.12, 4.48, 3.36, 1.68,
        0.56}, the contribution of each slice to the total would be
	{0.10, 0.40, 0.330, 0.15, 0.0 5}, since 
	<literal>0.10= 1.12/(1.12+4.48+3.36+1.68+0.56)</literal>, and
        the angular arcs of the wedges would be
	{36, 144, 108, 54, 18} degrees, since
	<literal>36=0.10*360</literal>.
      </para>

      <para>
        Pie plots do not have any sub-types.
      </para>

      <para>
        Pie plot styles provide two choices for the rendering of the
        pie chart, either with all slices linked into one overall
        circle, or with gaps between the slices. The size of the gap
        is a property of the pie plot which can be changed.
      </para>

      <figure id="fig-graph-types-example-pie">
        <title>An example of a pie plot</title>
              <screenshot>
                <mediaobject>
                  <imageobject>
                    <imagedata fileref="figures/graph-example-pie.png" 
                               format="PNG"  />
                    </imageobject>
                    <textobject>
                      <para>
		        A screenshot of a worksheet area showing a
                        data table and a pie plot made with those
                        data.
                      </para>
                    </textobject>
                    <caption>
                      <para>
	                This screenshot shows a table of data and a pie
                        plot. The data consist of a single data series
                        organized in a row and starting with the word
                        "Widgets". The series has values in five
                        categories. The legend includes the names of the
                        different data categories.
	              </para>
                    </caption>
                  </mediaobject>
                </screenshot>
      </figure>

      <para>
        Each pie plot contains a single series which can include three
        elements although only the value element is necessary. The
        series can have a 'Name' element, which is a single text entry
        used to identify the series, must have a 'Values' element,
        which is a sequence of numeric values, and may have a 'Label'
        element, which is a sequence of text entries used to identify
        the categories. All of these elements can be defined as
        references to a region of the worksheet, as literally defined
        entries, or as formula expressions which result in the correct
        type. The legend added to a pie plot identifies the different
        categories using the entries in the 'Label' element.
      </para>

<table frame='all'><title>The data in each pie plot series</title>
<tgroup cols='3' align='left' colsep='1' rowsep='1'>

<thead>
<row>
  <entry align="center">Element</entry>
  <entry align="center">Type</entry>
  <entry align="center">Example</entry>
</row>
</thead>
<tbody>
<row>
  <entry>Name</entry>
  <entry>A single textual entry labeling the data series.</entry>
  <entry>{"Widgets"}</entry>
</row>
<row>
  <entry>Value</entry>
  <entry>A list of numeric values.</entry>
  <entry>{1293, 2502, 3297, 1100, 2487}</entry>
</row>
<row>
  <entry>Label</entry>
  <entry>A list of textual entries labeling the category of each
  value. Generally, this series will have as many entries as there
  were in the 'Value' list. These will be used in the legend which
  may be displayed with the pie plot.</entry> 
  <entry>{"North", "South", "Central", "East", "West"}</entry>
</row>
</tbody>
</tgroup>
</table>

      <para>
        Pie plots do not have any sub-types but provide two icons to
        distinguish the style of the plot allowing a choice between
        pie plots which comprise a single circular area or plots with
        distinct pie slices separated by small gaps.
      </para>

      <variablelist>
        <title>Line plot sub-type and style options.</title>
	      <varlistentry>
	        <term>
		    <inlinemediaobject>
                      <imageobject>
                        <imagedata fileref="figures/chart_pie_1_1.png" />
                      </imageobject>
                      <textobject>
                        <phrase>
		          The icon for a pie plot of the style with
	                  joint slices. 
	                </phrase>
                      </textobject>
                    </inlinemediaobject>
	        </term>
	        <listitem>
	          <para>
		    The icon for a pie plot of the style with joint slices.
		  </para>
		</listitem>
	      </varlistentry>
	      <varlistentry>
	        <term>
		    <inlinemediaobject>
                      <imageobject>
                        <imagedata fileref="figures/chart_pie_2_1.png" />
                      </imageobject>
                      <textobject>
                        <phrase>
		          The icon for a pie plot of the style with separated 
	                  slices.
	                </phrase>
                      </textobject>
                    </inlinemediaobject>
	        </term>
	        <listitem>
	          <para>
		    The icon for a pie plot of the style with separated slices.
		  </para>
		</listitem>
	      </varlistentry>
	    </variablelist>


    </sect2>

    <sect2 id="sect-graphs-overview-types-polar" >
      <title>
        Polar Plots
      </title>
        <para>Work in Progress</para>
    </sect2>




    <sect2 id="sect-graphs-overview-types-radar" >
      <title>
        Radar Plots
      </title>

      <para>
        Radar plots present the numeric values of categorical data as
        a set of points plotted along a set of axes radiating from a
        central point, with as many axes as there are values in the
        series and with the points connected by a line, possibly with
        the interior of the shape filled in. Sequential data values
        are considered to belong to different categories and are
        plotted on separate axes which are not necessarily orthogonal
        and radiate from a central point. Sequential points are
        connected by a line with the final point connected back to the
        first to form a closed polygon. The data values from different
        series are assigned to categories based on the position of the
        value in the series, for example, the second data value taken
        from each series all share one category and will therefore all
        be plotted on the same axis.  The data values are plotted
        along the axis of each class according to their numeric value.
      </para>


      <para>
        Radar plots do not have any sub-types.
      </para>

      <para>
        Radar plot styles provide three choices for the rendering of the
        chart. The first style presents the radar chart as only a polygon of
        lines. The second style also includes a marker where the data
        values are plotted on each axis. The third style plots the
        radar chart as a filled polygon. 
      </para>


      <figure id="fig-graph-types-example-radar">
        <title>An example of radar plots</title>
              <screenshot>
                <mediaobject>
                  <imageobject>
                    <imagedata fileref="figures/graph-example-radar.png" 
                               format="PNG"  />
                    </imageobject>
                    <textobject>
                      <para>
		        A screenshot of a worksheet area showing a
                        data table and three radar charts made using
                        those data.
                      </para>
                    </textobject>
                    <caption>
                      <para>
	                This screenshot shows a table of data and three
                        radar plots. The data consist of three series
                        organized by row and starting with the words
                        "Widgets", "Gadgets", and "Lumpets". Each of
                        these series has values in five categories. The
                        three graphs illustrate the three sub-types of
                        radar plots, with the top left plot including
                        lines only, the top right plot including both
                        lines and markers on the points, and the bottom
                        middle plot using filled polygons.
	              </para>
                    </caption>
                  </mediaobject>
                </screenshot>
      </figure>

      <para>
        Each series in radar plots can include three main elements and
        two error elements, although only the value element is
        necessary. The series can have a 'Name' element, which is a
        single text entry used to identify the series, must have a
        'Values' element, which is a sequence of numeric values, and
        may have a 'Label' element, which is a sequence of text
        entries used to identify the categories.  All of these
        elements can be defined as references to a region of the
        worksheet, as literally defined entries, or as formula
        expressions which result in the correct type. The 'Label'
        element is shared by all of the series. The legend added to a
        radar plot identifies the different series, by default using
        the entries of the 'Name' element of each series. The two
        error elements include a list for errors in the positive
        direction and one for errors in the negative direction.
      </para>

<table frame='all'><title>The data in each radar plot series</title>
<tgroup cols='3' align='left' colsep='1' rowsep='1'>

<thead>
<row>
  <entry align="center">Element</entry>
  <entry align="center">Type</entry>
  <entry align="center">Example</entry>
</row>
</thead>
<tbody>
<row>
  <entry>Name</entry>
  <entry>A single textual element labeling the data series.</entry>
  <entry>{"Widgets"}</entry>
</row>
<row>
  <entry>Value</entry>
  <entry>A series of numeric values.</entry>
  <entry>{1293, 2502, 3297, 1100, 2487}</entry>
</row>
<row>
  <entry>Label</entry>
  <entry>A series of textual elements labeling each
  value. Generally, this series will have as many entries as there
  were in the 'Value' series.</entry> 
  <entry>{"North", "South", "Central", "East", "West"}</entry>
</row>
<row>
  <entry>Error (+)</entry>
  <entry>A list of numeric values with as many elements as there
  were in the 'Value' list. These values can be in the same units as
  the numeric values in the 'Value' list, can be proportions or can be
  proportions multiplied by one hundred.</entry> 
  <entry>{0.10, 0.12, 0.09, 0.11, 0.09}</entry>
</row>
<row>
  <entry>Error (-)</entry>
  <entry>A list of numeric values with as many elements as there
  were in the 'Value' list. These values can be in the same units as
  the numeric values in the 'Value' list, can be proportions or can be
  proportions multiplied by one hundred.</entry> 
  <entry>{0.08, 0.11, 0.10, 0.09, 0.11}</entry>
</row>
</tbody>
</tgroup>
</table>

      <para>
        Radar plots provide three icons distinguishing the three
        different styles.
      </para>



      <variablelist>
        <title>Radar plot sub-type and style options.</title>

	      <varlistentry>
	        <term>
		    <inlinemediaobject>
                      <imageobject>
                        <imagedata fileref="figures/chart_radar_1_1.png" />
                      </imageobject>
                      <textobject>
                        <phrase>
		          The icon for a radar plot with the style of
                          simple lines only.
	                </phrase>
                      </textobject>
                    </inlinemediaobject>
	        </term>
	        <listitem>
	          <para>
		    The icon for a radar plot with the style displaying
                    simple lines only.
		  </para>
		</listitem>
	      </varlistentry>

	      <varlistentry>
	        <term>
		    <inlinemediaobject>
                      <imageobject>
                        <imagedata fileref="figures/chart_radar_1_2.png" />
                      </imageobject>
                      <textobject>
                        <phrase>
		          The icon for a radar plot with the style
                          displaying both lines and point markers on
                          the data values.
	                </phrase>
                      </textobject>
                    </inlinemediaobject>
	        </term>
	        <listitem>
	          <para>
		    The icon for a radar plot with the style
                    displaying both lines and point markers on the
                    data values.
		  </para>
		</listitem>
	      </varlistentry>

	      <varlistentry>
	        <term>
		    <inlinemediaobject>
                      <imageobject>
                        <imagedata fileref="figures/chart_radar_1_3.png" />
                      </imageobject>
                      <textobject>
                        <phrase>
		          The icon for a radar plot with the style
                          displaying a filled area.
	                </phrase>
                      </textobject>
                    </inlinemediaobject>
	        </term>
	        <listitem>
	          <para>
		    The icon for a radar plot with the style
                    displaying a filled area.
		  </para>
		</listitem>
	      </varlistentry>

	    </variablelist>


    </sect2>


    <sect2 id="sect-graphs-overview-types-ring" >
      <title>
        Ring Plots
      </title>

      <para>
        Ring plots present the numeric values of categorical data as
        segments of circular rings. Sequential data values are
        considered to belong to different categories and are plotted
        with distinct patterns. The data values from different series
        are assigned to these categories based on the position of the
        value in the series, for example, the second data value taken
        from each series all share one category. The data values are
        used to determine the size of the arc based on the
        proportionate size of the data value to the sum of all data
        values in the series. For
        example, if the series had values { 1.12, 4.48, 3.36, 1.68,
        0.56}, the contribution of each ring section to the total would be
	{0.10, 0.40, 0.330, 0.15, 0.0 5}, since 
	<literal>0.10= 1.12/(1.12+4.48+3.36+1.68+0.56)</literal>, and
        the angular arcs of the sections would be
	{36, 144, 108, 54, 18} degrees, since
	<literal>36=0.10*360</literal>.
      </para>

      <para>
        Ring plots do not have any sub-types.
      </para>

      <para>
        Ring plot styles provide two choices. Ring plots can be
        plotted with all segments linked into a single overall ring,
        with different series plotted immediately adjacent to one
        another in sequentially larger rings. Alternatively, the
        segments of the outermost ring can be split and float a
        certain distance away from the next ring.
      </para>



      <figure id="fig-graph-types-example-ring">
        <title>An example of ring plots</title>
              <screenshot>
                <mediaobject>
                  <imageobject>
                    <imagedata fileref="figures/graph-example-ring.png" 
                               format="PNG"  />
                    </imageobject>
                    <textobject>
                      <para>
		        A screenshot of a worksheet area showing a
                        data table and two ring plots made with those
                        data.
                      </para>
                    </textobject>
                    <caption>
                      <para>
	                This screenshot shows a table of data and two
                        ring plots. The data consist of a single data
                        series organized in a row and starting with the
                        word "Widgets". The data consist of three series
                        organized by row and starting with the words
                        "Widgets", "Gadgets", and "Lumpets". Each of
                        these series has values in five categories. The
                        two graphs illustrate the two sub-types of ring
                        plots, the left most plot without any gaps and
                        the right most plot having the outer plot with
                        gaps.
	              </para>
                    </caption>
                  </mediaobject>
                </screenshot>
      </figure>

      <para>
        Each series in ring plots can include three main elements and
        two error elements, although only the value element is
        necessary. The series can have a 'Name' element, which is a
        single text entry used to identify the series, must have a
        'Values' element, which is a sequence of numeric values, and
        may have a 'Label' element, which is a sequence of text
        entries used to identify the categories.  All of these
        elements can be defined as references to a region of the
        worksheet, as literally defined entries, or as formula
        expressions which result in the correct type. The 'Label'
        element is shared by all of the series. The legend added to a
        ring plot identifies the different series, by default using
        the entries of the 'Name' element of each series. The two
        error elements include a list for errors in the positive
        direction and one for errors in the negative direction.
      </para>

<table frame='all'><title>The data in each ring plot series</title>
<tgroup cols='3' align='left' colsep='1' rowsep='1'>

<thead>
<row>
  <entry align="center">Element</entry>
  <entry align="center">Type</entry>
  <entry align="center">Example</entry>
</row>
</thead>
<tbody>
<row>
  <entry>Name</entry>
  <entry>A single textual element labeling the data series.</entry>
  <entry>{"Widgets"}</entry>
</row>
<row>
  <entry>Value</entry>
  <entry>A series of numeric values.</entry>
  <entry>{1293, 2502, 3297, 1100, 2487}</entry>
</row>
<row>
  <entry>Label</entry>
  <entry>A series of textual elements labeling each
  value. Generally, this series will have as many entries as there
  were in the "Value" series.</entry> 
  <entry>{"North", "South", "Central", "East", "West"}</entry>
</row>
<row>
  <entry>Error (+)</entry>
  <entry>A list of numeric values with as many elements as there
  were in the 'Value' list. These values can be in the same units as
  the numeric values in the 'Value' list, can be proportions or can be
  proportions multiplied by one hundred.</entry> 
  <entry>{0.10, 0.12, 0.09, 0.11, 0.09}</entry>
</row>
<row>
  <entry>Error (-)</entry>
  <entry>A list of numeric values with as many elements as there
  were in the 'Value' list. These values can be in the same units as
  the numeric values in the 'Value' list, can be proportions or can be
  proportions multiplied by one hundred.</entry> 
  <entry>{0.08, 0.11, 0.10, 0.09, 0.11}</entry>
</row>
</tbody>
</tgroup>
</table>

      <para>
        Ring plots provide two icons distinguishing the two different
        styles. 
      </para>



      <variablelist>
        <title>Ring plot sub-type and style options.</title>

	      <varlistentry>
	        <term>
		    <inlinemediaobject>
                      <imageobject>
                        <imagedata fileref="figures/chart_ring_1_1.png" />
                      </imageobject>
                      <textobject>
                        <phrase>
		          The icon for a ring plot with the style of
                          displaying series in contiguous rings.
	                </phrase>
                      </textobject>
                    </inlinemediaobject>
	        </term>
	        <listitem>
	          <para>
		    The icon for a ring plot with the style of
                    displaying series in contiguous rings.
		  </para>
		</listitem>
	      </varlistentry>

	      <varlistentry>
	        <term>
		    <inlinemediaobject>
                      <imageobject>
                        <imagedata fileref="figures/chart_ring_1_2.png" />
                      </imageobject>
                      <textobject>
                        <phrase>
		          The icon for a ring plot with the style of
                          displaying the outermost series separated
                          from the rest.
	                </phrase>
                      </textobject>
                    </inlinemediaobject>
	        </term>
	        <listitem>
	          <para>
		    The icon for a ring plot with the style of
                    displaying the outermost series separated
                    from the rest.
		  </para>
		</listitem>
	      </varlistentry>

	    </variablelist>

    </sect2>

    <sect2 id="sect-graphs-overview-types-statistics" >
      <title>
        Statistics Plots
      </title>
        <para>Work in Progress</para>
    </sect2>


    <sect2 id="sect-graphs-overview-types-suface" >
      <title>
        Surface Plots
      </title>
      <para>
        Surface plots are used to plot (<parameter>x</parameter>,<parameter>y
        </parameter>,<parameter>z</parameter>) points in three-dimensional space
        as a surface where z is interpreted as the height above the 
        <parameter>xy</parameter>-plane. 
        A &gnum; chart of course shows the projection of this surface in 3-space 
        onto a 2-dimensional sheet.
      </para>

      <para>
        Surface plot sub-types provide for 2 distinct ways of providing the data
        for a surface plot.
      </para>
      <para>The first subtype uses an <parameter>n</parameter> by 1 or 1 by
        <parameter>n</parameter> range for 
        the <parameter>x</parameter>-values, a second 1 by <parameter>m</parameter> 
        or <parameter>m</parameter> by 1 range for the <parameter>y</parameter>-values
        and an 
        <parameter>m</parameter> by <parameter>n</parameter> range for the 
        <parameter>z</parameter> values. The plotted points are constructed from 
        these three ranges in such a way that the <parameter>z</parameter> value 
        in the <parameter>i</parameter>th column and <parameter>j</parameter>th 
        row is combined with the <parameter>i</parameter>th <parameter>x</parameter> 
        value and the <parameter>j</parameter>th <parameter>y</parameter> value. 
        This subtype 
        then uses an <parameter>m</parameter> by <parameter>n</parameter> 
        grid for the surface. 
      </para>

      <figure id="fig-graph-types-example-surface-t1">
        <title>An example of a surface plot with rectangular data area</title>
              <screenshot>
                <mediaobject>
                  <imageobject>
                    <imagedata fileref="figures/graph-example-surface-t1.png" 
                               format="PNG"  />
                    </imageobject>
                    <textobject>
                      <para>
		        A screenshot of a worksheet with a data table
                and a graph containing an surface plot with rectangular 
                data area.
                      </para>
                    </textobject>
                  </mediaobject>
                </screenshot>
      </figure>

      <para>The second subtype uses a direct listing of the 
        <parameter>n</parameter> points. The <parameter>x</parameter> values
        are specified with an <parameter>n</parameter> by 1 range, so are the 
        <parameter>y</parameter> and <parameter>z</parameter> values. The 
        <parameter>i</parameter>th 
        <parameter>z</parameter> value is then combined with the 
        <parameter>i</parameter>th <parameter>x</parameter> and 
        <parameter>i</parameter>th <parameter>y</parameter> value to obtain the 
        points to be plotted.It is not necessary to provide the same number of 
        <parameter>y</parameter> 
        coordinates for each <parameter>x</parameter> coordinate or vice versa. 
        &gnum; will interpolate
        missing values. For this purpose one needs to specify the number of 
        (equidistant) rows and columns to be used for the surface grid. This grid
        need not align with the provided coordinates.
      </para>


      <figure id="fig-graph-types-example-surface-t12">
        <title>An example of a surface plot with x,y, and z series</title>
              <screenshot>
                <mediaobject>
                  <imageobject>
                    <imagedata fileref="figures/graph-example-surface-t2.png" 
                               format="PNG"  />
                    </imageobject>
                    <textobject>
                      <para>
		        A screenshot of a worksheet with a data table
                        and a graph containing an surface plot with xyz series.
                      </para>
                    </textobject>
                  </mediaobject>
                </screenshot>
      </figure>

      <para>
        Surface plots do not have any pre-defined styles.
      </para>



<table frame='all'><title>The data in each surface plot series with rectangular 
                            data area
                    </title>
<tgroup cols='3' align='left' colsep='1' rowsep='1'>
<thead>
<row>
  <entry align="center">Element</entry>
  <entry align="center">Type</entry>
  <entry align="center">Example</entry>
</row>
</thead>
<tbody>
<row>
  <entry>Name</entry>
  <entry>A single textual element labeling the data series. These will
    be used in the legend which may be displayed with the surface
    plot.</entry> 
  <entry>{"Widgets"}</entry>
</row>
<row>
  <entry>X</entry>
  <entry>An optional series of numeric values to be used for the <parameter>x</parameter> coordinates of the grid. This defaults to {1,2,&hellip;,n}.</entry>
  <entry>{1,3,5,6,8,9}</entry>
</row>
<row>
  <entry>Y</entry>
  <entry>An optional series of numeric values to be used for the <parameter>y</parameter> coordinates of the grid. This defaults to {1,2,&hellip;,n}.</entry>
  <entry>{1,1.5,2,2.5}</entry>
</row>
<row>
  <entry>Z</entry>
  <entry>A rectangular range of numbers where the number in <parameter>j</parameter>th 
        row and <parameter>i</parameter>th column is the height of the 
        <parameter>(i,j)</parameter> grid point.</entry> 
  <entry>A2:J15</entry>
</row>
</tbody>
</tgroup>
</table>

<table frame='all'><title>The data in each surface plot series with <parameter>xyz</parameter> series.
                    </title>
<tgroup cols='3' align='left' colsep='1' rowsep='1'>
<thead>
<row>
  <entry align="center">Element</entry>
  <entry align="center">Type</entry>
  <entry align="center">Example</entry>
</row>
</thead>
<tbody>
<row>
  <entry>Name</entry>
  <entry>A single textual element labeling the data series. These will
    be used in the legend which may be displayed with the surface
    plot.</entry> 
  <entry>{"Widgets"}</entry>
</row>
<row>
  <entry>X</entry>
  <entry>A series of numeric values to be used for the <parameter>x</parameter> coordinates of the grid.</entry>
  <entry>{1,1.5,2,2.5}</entry>
</row>
<row>
  <entry>Y</entry>
  <entry>A series of numeric values to be used for the <parameter>y</parameter> coordinates of the grid.</entry>
  <entry>{1,1.5,2,2.5}</entry>
</row>
<row>
  <entry>Z</entry>
  <entry>A series of numeric values to be used for the <parameter>z</parameter> coordinates of the grid.</entry>
  <entry>{1,1.5,2,2.5}</entry>
</row>
</tbody>
</tgroup>
</table>


      <para>
        Surface plots provide two icons to choose one of the two
      surface plot sub-types.
      </para>



      <variablelist>
        <title>Surface plot sub-type and style options.</title>
	      <varlistentry>
	        <term>
		    <inlinemediaobject>
                      <imageobject>
                        <imagedata fileref="figures/chart_surface_1.png" />
                      </imageobject>
                      <textobject>
                        <phrase>
		          The icon for a surface plot of the sub-type with
	                  rectangular data area.
	                </phrase>
                      </textobject>
                    </inlinemediaobject>
	        </term>
	        <listitem>
	          <para>
		    The icon for an area plot of the sub-type with rectangular data area.
		  </para>
		</listitem>
	      </varlistentry>

	      <varlistentry>
	        <term>
		    <inlinemediaobject>
                      <imageobject>
                        <imagedata fileref="figures/chart_surface_2.png" />
                      </imageobject>
                      <textobject>
                        <phrase>
		          The icon for a surface plot of the sub-type with
                      xyz series.
	                </phrase>
                      </textobject>
                    </inlinemediaobject>
	        </term>
	        <listitem>
	          <para>
		    The icon for an area plot of the sub-type with
                    xyz series.
		  </para>
		</listitem>
	      </varlistentry>

	    </variablelist>


    </sect2>



    <sect2 id="sect-graphs-overview-types-xy" >
      <title>
        XY Scatterplots
      </title>

      <para>
         The data values of two series of equal length are plotted on
	 the Cartesian (X-Y) plane, the value from the first series
	 determining the position of the plotted symbol along the X
	 axis, and the value from the second series determining the
	 position of the plotted symbol along the Y axis. Data can be
	 plotted as points only, with each pair of data series having
	 different symbols, or, alternatively, sequential data pairs
	 can be connected by a line, or, finally, both symbols and a
	 connecting line can be used.
      </para>

      <figure id="fig-graph-types-example-xyplot">
        <title>An example of an XY scatterplot</title>
              <screenshot>
                <mediaobject>
                  <imageobject>
                    <imagedata fileref="figures/graph-example-xyplot.png" 
                               format="PNG"  />
                    </imageobject>
                    <textobject>
                      <para>
		        A screenshot of an XY scatterplot and the data
                        used to generate the plot.
                      </para>
                    </textobject>
                    <caption>
                      <para>
	                This screenshot shows a data table with two
                        different series highlighted which are usable in
                        a scatterplot. Each series is comprised of two
                        lists of numeric values. The screenshot also
                        shows the scatterplot made from these two data
                        series.
	              </para>
                    </caption>
                  </mediaobject>
                </screenshot>
      </figure>

      <para>
        Each series in a scatterplot can include three core components
        and four optional error components. The series may have a
        name, a single text value which will identify the series in
        the <interface>Graph Guru</interface> and in any legend
        attached to the chart. The series must have two lists of
        quantitative values, a list of X values and a list of Y
        values, which must have an equal number of elements. The
        series may also contain lists of error values for each of the
        X and Y lists with a positive and a negative component for
        each.
      </para>

<table frame='all'><title>The data in each XY scatterplot series</title>
<tgroup cols='3' align='left' colsep='1' rowsep='1'>

<thead>
<row>
  <entry align="center">Element</entry>
  <entry align="center">Type</entry>
  <entry align="center">Example</entry>
</row>
</thead>
<tbody>
<row>
  <entry>Name</entry>
  <entry>A single textual element labeling the data series.</entry>
  <entry>{"Series1"}</entry>
</row>
<row>
  <entry>X</entry>
  <entry>A list of numeric values, which will place the values along
  the horizontal axis.</entry>
  <entry>{14.5, 2.8, 11.8, 5.7, 8.2}</entry>
</row>
<row>
  <entry>Y</entry>
  <entry>A second list of numeric values, which will place the values along
  the vertical axis.</entry>
  <entry>{154, 29, 63, 90, 107}</entry>
</row>
<row>
  <entry>X Error (+)</entry>
  <entry>A list of numeric values with as many elements as there
  were in the 'X' list. These values can be in the same units as
  the numeric values in the 'X' list, can be proportions or can be
  proportions multiplied by one hundred.</entry> 
  <entry>{0.10, 0.12, 0.09, 0.11, 0.09}</entry>
</row>
<row>
  <entry>X Error (-)</entry>
  <entry>A list of numeric values with as many elements as there
  were in the 'X' list. These values can be in the same units as
  the numeric values in the 'Value' list, can be proportions or can be
  proportions multiplied by one hundred.</entry> 
  <entry>{0.08, 0.11, 0.10, 0.09, 0.11}</entry>
</row>
<row>
  <entry>Y Error (+)</entry>
  <entry>A list of numeric values with as many elements as there were
  in the 'Y' list, and therefore in the 'X' list. These values can be
  in the same units as the numeric values in the 'Y' list, can be
  proportions or can be proportions multiplied by one hundred.</entry>
  <entry>{0.09, 0.11, 0.10, 0.12, 0.09}</entry>
</row>
<row>
  <entry>Y Error (-)</entry>
  <entry>A list of numeric values with as many elements as there were
  in the 'Y' list, and therefore in the 'X' list. These values can be
  in the same units as the numeric values in the 'Y' list, can be
  proportions or can be proportions multiplied by one hundred.
</entry> 
  <entry>{0.10, 0.09, 0.08, 0.11, 0.11}</entry>
</row>
</tbody>
</tgroup>
</table>

      <para>
        XY scatterplots provide three icons to select between
        different style options. The plots can be rendered with
        markers at each point, with markers at each point and a line
        joining adjacent values in the data lists, or with a line but
        no markers. 
      </para>



      <variablelist>
        <title>XY scatterplot style options.</title>

	      <varlistentry>
	        <term>
		    <inlinemediaobject>
                      <imageobject>
                        <imagedata fileref="figures/chart_scatter_1_1.png" />
                      </imageobject>
                      <textobject>
                        <phrase>
		          The icon for scatter plot of style with only
                          a marker at each point.
	                </phrase>
                      </textobject>
                    </inlinemediaobject>
	        </term>
	        <listitem>
	          <para>
		    The icon for scatterplot of style with only
                    a marker at each point.
		  </para>
		</listitem>
	      </varlistentry>

	      <varlistentry>
	        <term>
		    <inlinemediaobject>
                      <imageobject>
                        <imagedata fileref="figures/chart_scatter_3_1.png" />
                      </imageobject>
                      <textobject>
                        <phrase>
		          The icon for scatter plot of style with a
                          marker at each point and a line between
                          adjacent points in the value lists.
	                </phrase>
                      </textobject>
                    </inlinemediaobject>
	        </term>
	        <listitem>
	          <para>
		    The icon for scatterplot of style with a
                          marker at each point and a line between
                          adjacent points in the value lists.
		  </para>
		</listitem>
	      </varlistentry>

	      <varlistentry>
	        <term>
		    <inlinemediaobject>
                      <imageobject>
                        <imagedata fileref="figures/chart_scatter_3_2.png" />
                      </imageobject>
                      <textobject>
                        <phrase>
		          The icon for scatter plot of style with only
                          a line between adjacent points in the value lists.
	                </phrase>
                      </textobject>
                    </inlinemediaobject>
	        </term>
	        <listitem>
	          <para>
		    The icon for scatterplot of style with only
                    a line between adjacent points in the value lists.
		  </para>
		</listitem>
	      </varlistentry>

      </variablelist>


    </sect2>

















  </sect1>









  <sect1 id="sect-graphs-elementProperties">
    <title>Configuring Graph Element Properties</title>

    <para>
      Graphs in &gnum; can be configured
      extensively using the <interface>Graph Guru</interface>. In this
      way, the user can determine the data used in the plots, the
      names and labels associated with the data, the numerical values
      of the axes and the stylistic presentation of all the graphical
      elements.
    </para>

    <para>
      Graphs are configured element by element, first by selecting the
      element name in the top left area of the second panel of the
      <interface>Graph Guru</interface>, shown as area
      <guimenu>F</guimenu> in <xref linkend="fig-graphguru-panels"/>,
      and, second, by altering the properties in the bottom area of
      the second panel of the
      <interface>Graph Guru</interface>, shown as area
      <guimenu>J</guimenu>. These changes will be applied to the graph
      only when the <guibutton>OK</guibutton> button is pressed.
    </para>

    <note>
    <para>
      A number of properties of the graph are configured using the
      &gnum; entry box shown in <xref
      linkend="fig-widget-entryBox"/>. 

      <figure id="fig-widget-entryBox">
        <title>The data entry box widget</title>
	 <screenshot>
          <mediaobject> 
	    <imageobject> 
	      <imagedata fileref="figures/widget-entryBox-outlined.png"
	                 format="PNG" />
	    </imageobject>
	    <textobject>
	      <para> 
	        This screenshot depicts the widget used to enter data
	        as defined values, references or expressions.
	      </para>
	    </textobject>
	    <caption>
	      <para>
	        The data entry box widget allows users to enter data as
	        defined values (e.g. "A name", 123, or {12,32,14}), as references
	        (e.g. 'Sheet1!A2:B4'), or as expressions (e.g. sin({11,16}) ).
	      </para>
	    </caption>
	  </mediaobject>
	</screenshot>
      </figure>

      Information can be inserted to the data entry box, first, by
      selecting the box with a mouse click and, then, either typing
      data on a keyboard or using the mouse to select a region of the
      worksheet.

    </para>
    </note>




    <sect2 id="sect-graphs-elementProperties-backPanels">
      <title>Background Panels: Graphs &amp; Charts</title>

      <para>
        Several elements of the graph function as background panels
        for the other elements. These panels can be configured to
        display a visible background consisting of a solid color, a
        pattern, a gradient, or an image. Alternatively, the panel can
        be made transparent to show the underlying panel, if
        any. Where there are only transparent panels, the worksheet
        itself will be visible behind the graph.
      </para>

      <figure id="fig-graphics-plots-elementProperties-backPanels">
        <title>The background panel configuration.</title>
	 <screenshot>
          <mediaobject> 
	    <imageobject> 
	      <imagedata fileref="figures/graphguru-backPanels-none.png"
	                 format="PNG" />
	    </imageobject>
	    <textobject>
	      <para> 
	        This screenshot depicts the two elements of background
	        panels which can be configured, the background fill
	        and the outline. 
	      </para>
	    </textobject>
	    <caption>
	      <para>
	        This screenshot depicts the two elements of background
	        panels which can be configured, the background fill
	        and the outline. 
	      </para>
	    </caption>
	  </mediaobject>
	</screenshot>
      </figure>

      <para>
        The background panel <guilabel>Fill</guilabel> refers to the
        area which is behind the entire component. The
        <guilabel>Outline</guilabel> refers to a solid box which will
        be drawn around the edge of the component.
      </para>

      <para>
        The <guilabel>Outline</guilabel> can be configured by
        selecting a color using the color picker widget and by
        choosing a size using the spin button box. A size of '-1'
        indicates that no line will be drawn, whereas sizes zero and
        above indicate the size of the line that will be drawn.
      </para>

      <para>
        The <guilabel>Fill</guilabel> can be configured to be a
        pattern, which includes a solid color, a gradient or an image.
      </para>

      <figure id="fig-graphics-plots-elementProperties-backPanels-pattern">
        <title>The pattern background panel fill configuration.</title>
	 <screenshot>
          <mediaobject> 
	    <imageobject> 
	      <imagedata fileref="figures/graphguru-backPanels-pattern.png"
	                 format="PNG" />
	    </imageobject>
	    <textobject>
	      <para> 
	        This screenshot depicts the configuration properties
	        for the pattern background panel fill.
	      </para>
	    </textobject>
	    <caption>
	      <para>
	        This screenshot depicts the configuration properties for
	        the pattern background panel fill.
	      </para>
	    </caption>
	  </mediaobject>
	</screenshot>
      </figure>

      <para>
        The fill using a pattern enables the panel background to
        consist either of a solid color, or of a solid color overlain
        by a pattern. The top drop down button, labeled
        <guilabel>Pattern</guilabel>, allows the user to select the
        pattern overlay from a number of different standard
        patterns. The pattern in the top left corner is an empty
        pattern which allows the background color indicated in the
        third drop down button to fill the panel. The middle drop down
        button, labeled <guilabel>Foreground</guilabel>, allows the
        user to select the color of the overlay in the pattern. The
        bottom drop down button, labeled
        <guilabel>Background</guilabel>, allows the user to select the
        color of the underlay. If the pattern is empty, the color of
        the Background will be the color of the entire panel.
      </para>

      <note>
        <para>
	  If all of these buttons appear black, change the color of
	  the <guilabel>Background</guilabel> to white to see the
	  pattern and foreground color.
	</para>
      </note>

      <figure id="fig-graphics-plots-elementProperties-backPanels-gradient">
        <title>The gradient background panel fill configuration.</title>
	 <screenshot>
          <mediaobject> 
	    <imageobject> 
	      <imagedata fileref="figures/graphguru-backPanels-gradient.png"
	                 format="PNG" />
	    </imageobject>
	    <textobject>
	      <para> 
	        This screenshot depicts the configuration properties
	        for the gradient background panel fill.
	      </para>
	    </textobject>
	    <caption>
	      <para>
	        This screenshot depicts the configuration properties for
	        the gradient background panel fill. 
	      </para>
	    </caption>
	  </mediaobject>
	</screenshot>
      </figure>

      <para>
        The background panel can be filled with a gradient
        transitioning either between two colors or between a color and
        a tone, either white or black. The top drop down button,
        labeled <guilabel>Direction</guilabel>, gives the user a
        number of choices for the direction in which the gradient will
        operate. The drop down button named <guilabel>Type</guilabel>
        allows the user to pick between gradients which transition
        between two colors, the <guilabel>2 Colors</guilabel> option,
        and gradients that transition from a color to pure white or
        pure black, the <guilabel>Brightness</guilabel> option. The
        drop down buttons for the <guilabel>Start</guilabel> and
        <guilabel>End</guilabel> colors allow the user to pick the
        colors in the gradient. For the brightness gradients, a slider
        allows the user to select the transition direction. Moving the
        slider toward <guilabel>Brighter</guilabel> will fade the
        color to white whereas moving the slider toward
        <guilabel>Darker</guilabel> will fade the color toward black.
      </para>

      <note>
        <para>
	  If all of these buttons appear black, change the color of
	  the <guilabel>Start</guilabel> button to white to see the
	  gradient.
	</para>
      </note>

      <figure id="fig-graphics-plots-elementProperties-backPanels-image">
        <title>The image background panel fill configuration.</title>
	 <screenshot>
          <mediaobject> 
	    <imageobject> 
	      <imagedata fileref="figures/graphguru-backPanels-image.png"
	                 format="PNG" />
	    </imageobject>
	    <textobject>
	      <para> 
	        This screenshot depicts the configuration properties
	        for the image background panel fill.
	      </para>
	    </textobject>
	    <caption>
	      <para>
	        This screenshot depicts the configuration properties for
	        the image background panel fill. 
	      </para>
	    </caption>
	  </mediaobject>
	</screenshot>
      </figure>

      <para>
        The image background fill type allows the user to select an
        image to fill the background of the panel. The image can be in
        any file format supported by the <literal>gdk-pixbuf</literal>
        library as explained in <xref
        linkend="sect-graphics-images"/>. The image can be fit in one
        of two ways. The image fit can be stretched so the image fills
        the whole panel area or the image fit can be wallpapered where
        the image is repeated in a tile pattern to fill up the whole
        background. The button labeled <guilabel>Select</guilabel>
        allows the user to call the file selector and choose the file
        which contains the desired image. On the GNOME desktop, the
        file chooser has a preview area to see the image before adding
        it. The size of the image, in pixels, is displayed in the
        configuration dialog as '# x #' where the number symbol
        indicates the number of pixels, and the number of pixels in
        each row comes before the number in each column.
      </para>

    </sect2>




    <sect2 id="sect-graphs-elementProperties-title">
      <title>Titles and Axis Labels</title>

      <para>
        Both <guilabel>Title</guilabel> and <guilabel>Axis
        Labels</guilabel> can be configured using three tabs. The
        first tab allows the user to configure the background panel of
        the title or axis label. The second tab allows the user to
        select the font that will be used to display the words in the
        title or axis label. The third tab allows the user to input
        the actual words which will be used in the graph.
      </para>

     <figure id="fig-graphics-plots-elementProperties-title-font">
        <title>The font selection for Titles and Axis Labels.</title>
	 <screenshot>
          <mediaobject> 
	    <imageobject> 
	      <imagedata fileref="figures/graphguru-title-font.png"
	                 format="PNG" />
	    </imageobject>
	    <textobject>
	      <para> 
	        This screenshot depicts the font configuration panel
	        for titles and axis labels in the <interface>Graph
	        Guru</interface>. 
	      </para>
	    </textobject>
	    <caption>
	      <para>
	        This screenshot depicts the font configuration panel
	        for titles and axis labels in the <interface>Graph
	        Guru</interface>. 
	      </para>
	    </caption>
	  </mediaobject>
	</screenshot>
      </figure>

      <para>
        The <guilabel>Style</guilabel> tab allows the user to
        configure the background panel in the same way this was
        configured for graphs, charts and grids, as was explained
        above in <xref
        linkend="sect-graphs-elementProperties-backPanels"/>. 
      </para>


       <para>
        The <guilabel>Font</guilabel> tab is shown in <xref
        linkend="fig-graphics-plots-elementProperties-title-font" />
        and consists of three column lists. The first column list
        allows the user to select the font name by scrolling the list
        and then clicking on the desired name. The currently selected
        font name is highlighted in light blue. The second column list
        allows the user to select the font style including italic and
        bold styles. The third column list allows the user to select a
        size for the font. The preview area contains a few characters
        to illustrate the appearance of the currently selected
        combination. 
      </para>

      <para>
        The <guilabel>Data</guilabel> tab displays a single entry box
        in which the user can place the words which will appear in the
        title or in the label. The user can simply type the text, can
        add a reference to a section of the worksheet or can add an
        expression which results in a text value.
      </para>

     </sect2>




    <sect2 id="sect-graphs-elementProperties-legend">
      <title>Chart Legends</title>

      <para>
        Chart legends provide a graphical explanation of the data
        plotted with the names and style of the
        different series, or categories, plotted in each chart.  
        Legends are configured through two tabs, labeled
        <guilabel>Style</guilabel> and <guilabel>Font</guilabel>. The
        <guilabel>Style</guilabel>  tab 
        allows for the configuration of the background pane in a manner
        analogous to the graph, chart and grid background panes,
        explained in  <xref
        linkend="sect-graphs-elementProperties-backPanels"/>.
        The <guilabel>Font</guilabel> tab allows the configuration of
        the font that will appear in the legend. This configuration is
        identical to the configuration of the title and axis label
        fonts presented in <xref
        linkend="sect-graphs-elementProperties-title"/>. 
      </para>

    </sect2>





    <sect2 id="sect-graphs-elementProperties-axes">
      <title>Axes</title>

      <para>
        Axes are used in several different kinds of plots to provide
        quantitative indexes for the scale of each plot
        direction. &gnum; uses four
        different kinds of axes. <guilabel>Category</guilabel> axes do
        not provide a quantitative scale but merely distinguish each
        different category by providing space for the values of the
        category along the axis. <guilabel>Continuous</guilabel> axes
        provide a quantitative measure of each value based on the
        projection of that value onto the
        axis. <guilabel>Radial</guilabel> axes are used in radar plots
        and are continuous axes which radiate from a central
        point. <guilabel>Circular</guilabel> axes have not yet been
        implemented.
      </para>

      <para>
        Line, column and area charts use a category axis to separate
        the categories along the horizontal direction and a continuous
        axis to distinguish values in the vertical direction. Bar
        charts reverse these two axes. XY scatter plots and bubble
        plots use two continuous axes, one in the horizontal
        direction, the X-axis, and one in the vertical direction, the
        Y-axis. Radar plots use three or more continuous axes
        radiating from a central point. Pie and Ring plots do not use
        any axes.
      </para>

      <sect3 id="sect-graphs-elementProperties-axes-categorical">
        <title>Category Axes</title>

	<para>
	  Category axes distinguish the different categories of each
	  value in a category series such as the series in line, bar,
	  column and area plots.
	</para>

        <figure id="fig-graphics-plots-elementProperties-axes-category-bounds">
          <title>Category axis bounds configuration.</title>
	  <screenshot>
            <mediaobject> 
	      <imageobject> 
	        <imagedata fileref="figures/graphguru-axes-category-bounds.png"
	                 format="PNG" />
	      </imageobject>
	      <textobject>
	        <para> 
	          This screenshot depicts the 'bounds' tab for the
	          configuration of a category axis. 
	        </para>
	      </textobject>
	    </mediaobject>
	  </screenshot>
        </figure>

	<para>
	  The <guilabel>Bounds</guilabel> tab allows the user to
	  override the automatic configuration of axis tick marks and
	  labels. Each of the three choices can be over-ridden by
	  deselecting the check box on the left. The check boxes can
	  be deselected by placing the mouse pointer over the check
	  box and clicking with the primary mouse button. When a check
	  box is unselected, the entry box will become active allowing
	  the user to input a different value than the default. The
	  first check box controls the number of tick marks, allowing
	  tick marks to appear after the integer number of categories
	  shown. The second check box controls the number of labels
	  displayed, allowing a regular number of category labels to
	  be skipped. The third check box controls the placement of
	  the orthogonal axis relative to the category axis.
        </para>

        <figure id="fig-graphics-plots-elementProperties-axes-categry-style">
          <title>Category axis line style configuration.</title>
	  <screenshot>
            <mediaobject> 
	      <imageobject> 
	        <imagedata fileref="figures/graphguru-axes-category-style.png"
	                 format="PNG" />
	      </imageobject>
	      <textobject>
	        <para> 
	          This screenshot depicts the 'style' tab for the
	          configuration of a category axis.
	        </para>
	      </textobject>
	    </mediaobject>
	  </screenshot>
        </figure>

	<para>
	  The <guilabel>Style</guilabel> tab allows the user to
	  configure the line style of the axis, including the color
	  and thickness of the line. The drop down button labeled
	  <guilabel>Color</guilabel> can be clicked to expose the
	  color picker panel which allows the user to select a new
	  color either simply by clicking on an icon or by using the
	  color picker wheel. The size spin button allows a user to
	  change the thickness of the axis by typing a new number in
	  the text box or by clicking on the arrows. A value of '-1'
	  in this box will cause the axis not to be drawn.
	</para>

	<para>
	  The <guilabel>Font</guilabel> tab allows the user to
	  configure the font used to label the separate
	  categories. The font configuration is performed in the same
	  way as the font configuration for titles and axis labels
	  which was explained in <xref
	  linkend="sect-graphs-elementProperties-title" />. 
	</para>

        <figure id="fig-graphics-plots-elementProperties-axes-categry-details">
          <title>The category axis details configuration.</title>
	  <screenshot>
            <mediaobject> 
	      <imageobject> 
	        <imagedata fileref="figures/graphguru-axes-category-details.png"
	                 format="PNG" />
	      </imageobject>
	      <textobject>
	        <para> 
	          This screenshot depicts the 'details' tab for the
	          configuration of a category axis.
	        </para>
	      </textobject>
	    </mediaobject>
	  </screenshot>
        </figure>

	<para>
	  The <guilabel>Details</guilabel> tab allows a user to
	  configure other aspects of the axis. 
	</para>

	<para>
	  The <guilabel>Position</guilabel> of the axis is placed in
	  the <guilabel>Low</guilabel> position by default. This can
	  be altered by pressing the radio button in front of the
	  <guilabel>High</guilabel> label which will move the internal
	  button and will alter the position of the axis, moving it
	  either to the top of the graph for horizontal axes, or to
	  the right of the graph for vertical axes.
	</para>

	<para>
	  The <guilabel>Mapping</guilabel> of the axis can be changed
	  simply by clicking on the check box. This will cause a check
	  mark to appear in the box and will invert the axis so that
	  the order of the categories will become reversed.
        </para>

	<para>
	  The <guilabel>Major ticks</guilabel> displayed on the axis
	  can be altered. The labels shown in the plot can be hidden
	  by unchecking the check box in front of the 'Show Labels'
	  text by placing the mouse cursor over the box and clicking
	  with the primary mouse button. The ticks on the axis can be
	  hidden or can be displayed on the outside of the graph, or
	  on the inside of the graph, or on both sides depending on
	  which of the two boxes are checked.
	</para>

	<para>
	  The <guilabel>Minor ticks</guilabel> do not currently have
	  any effect for category axes.
	</para>


      </sect3>



      <sect3 id="sect-graphs-elementProperties-axes-continuous">
        <title>Continuous Axes: Linear, Radial &amp; Circular</title>

	<para>
	  Continuous axes are configured in much the same way as
	  category axes except for some minor differences.
	</para>

        <figure id="fig-graphics-plots-elementProperties-axes-continuous-bounds">
          <title>Continuous axis bounds configuration.</title>
	  <screenshot>
            <mediaobject> 
	      <imageobject> 
	        <imagedata fileref="figures/graphguru-axes-continuous-bounds.png"
	                 format="PNG" />
	      </imageobject>
	      <textobject>
	        <para> 
	          This screenshot depicts the 'bounds' tab for the
	          configuration of a continuous axis. 
	        </para>
	      </textobject>
	    </mediaobject>
	  </screenshot>
        </figure>

	<para>
	  The <guilabel>Bounds</guilabel> tab allow users to configure
	  the limits and intervals of a continuous axis. The meaning of the 
	  values for <guilabel>Major Ticks</guilabel> and 
	  <guilabel>Minor Ticks</guilabel> depends on the type of continuous axes:
	  <variablelist>
	    <varlistentry>
	      <term>
		Continuous Axes with Linear Scale
	      </term>
	      <listitem>
		<para>
		  The <guilabel>Major Ticks</guilabel> value gives the distance
		  between major ticks and the <guilabel>Minor Ticks</guilabel>
		  value the distance between minor ticks.
		</para>
	      </listitem>
	    </varlistentry>
	    <varlistentry>
	      <term>
		Continuous Axes with Logarithmic Scale
	      </term>
	      <listitem>
		<para>
		   The <guilabel>Major Ticks</guilabel> value gives the number of
		   decades (powers of 10) between major ticks. The 
		   <guilabel>Minor Ticks</guilabel> value gives the 
		   number of minor ticks between major ticks.
		</para>
		<note>
		  <para>
		    If the <guilabel>Major Ticks</guilabel> value is <parameter>N</parameter>,
		    then the <guilabel>Minor Ticks</guilabel> value can be
		    <parameter>0</parameter>, <parameter>N&#x2212;1</parameter>, or <parameter>9N&#x2212;1</parameter>.
		  </para>
		</note>
	      </listitem>
	    </varlistentry>
	  </variablelist>
	</para>
	
	<para>
	  The <guilabel>Style</guilabel> tab changes the linear style
	  of the axis in the same way as it acted on category
	  axes. The explanation given in <xref
	  linkend="sect-graphs-elementProperties-axes-categorical"/>
	  apply equally well to continuous axes.
	</para>

	<para>
	  The <guilabel>Font</guilabel> tab also allows users to
	  configure the font used in the numeric markers along the
	  axis. Selecting the font for a continuous axis works in the
	  same way as for a category axis as was explained in <xref
	  linkend="sect-graphs-elementProperties-axes-categorical"/>.
	</para>

	<para>
	  The <guilabel>Details</guilabel> tab has two small
	  differences compared to category axes. The mapping of the axis
	  can be altered from a linear scale to a logarithmic scale by
	  clicking on the drop down box and dragging to the entry
	  labeled <guimenuitem>Log</guimenuitem>. The minor ticks,
	  whose size was configured in the <guilabel>Bounds</guilabel>
	  tab, are displayed for continuous axes unlike for
	  categorical axes.
	</para>

        <figure id="fig-graphics-plots-elementProperties-axes-continuous-format">
          <title>Continuous axis format configuration.</title>
	  <screenshot>
            <mediaobject> 
	      <imageobject> 
	        <imagedata fileref="figures/graphguru-axes-continuous-format.png"
	                 format="PNG" />
	      </imageobject>
	      <textobject>
	        <para> 
	          This screenshot depicts the 'format' tab for the
	          configuration of a continuous axis. 
	        </para>
	      </textobject>
	    </mediaobject>
	  </screenshot>
        </figure>

	<para>
	  The <guilabel>Format</guilabel> tab allow users to configure
	  the numeric type of the elements on a continuous axis. This
	  configuration parallels the configuration of the numeric
	  type of a worksheet cell as explained in <xref
	  linkend="number-formatting-overview"/>. 
	</para>


      </sect3>

      <sect3 id="sect-graphs-elementProperties-axes-grids">
        <title>Grids</title>

	<para>
	  Users can add both major and minor grids to an axis. Grids are lines that
	  are perpendicular to the axis at fixed intervals. An example of major (in blue) and
	  minor (in green) grids attached to a vertical axis are shown in <xref
	  linkend="fig-graphics-plots-axes-grid"/>.
	</para>

        <figure id="fig-graphics-plots-axes-grid">
          <title>Major and Minor Grids.</title>
	  <screenshot>
            <mediaobject> 
	      <imageobject> 
	        <imagedata fileref="figures/graph-axes-grid.png"
	                 format="PNG" />
	      </imageobject>
	      <textobject>
	        <para> 
	          This screenshot shows a plot with major (in blue) and
		  minor (in green) grids attached to the vertical axis. 
	        </para>
	      </textobject>
	    </mediaobject>
	  </screenshot>
        </figure>

	<para>
	  To add either a major or minor grid to an axis, the user selects the
	  appropriate axis in the hierarchy tree of graph components, clicks
	  the <guibutton>Add</guibutton> button below the hierarchy, and selects
	  either <guimenu>MajorGrid</guimenu> or <guimenu>MinorGrid</guimenu>.
	</para>

	<para>
	  When a grid has been added to an axis, it can be selected in the hierarchy
	  tree of graph components and customized in its configuration tab. One can
	  specify the style, color, and thickness (size) of the grid lines as well as
	  specify a fill to be applied to the space between every second pair of
	  consecutive grid lines.
	</para>



      </sect3>

    </sect2>





    <sect2 id="sect-graphs-elementProperties-plots">
      <title>Plots</title>

      <para>
        Certain of the properties of plots are assigned directly to
        the plot element and are configured when the plot element
        itself is selected.
      </para>

     <para>
	Line plots, Area plots, and XY scatter plots do not have any
	plot level properties which can be configured.
      </para>



      <sect3 id="sect-graphs-elementProperties-plots-bubble">
        <title>Bubble plots</title>

	<para>
	  The bubbles in bubble plots are used to represent a third
	  data component with the size of the bubble representing the
	  value of the third component.
	</para>

        <figure id="fig-graphics-plots-elementProperties-plots-bubble">
          <title>The configurable properties of a bubble plot.</title>
	  <screenshot>
            <mediaobject> 
	      <imageobject> 
	        <imagedata fileref="figures/graphguru-plot-bubble.png"
	                 format="PNG" />
	      </imageobject>
	      <textobject>
	        <para> 
	          This screenshot depicts the properties of a bubble plot
	          which can be configured. 
	        </para>
	      </textobject>
	    </mediaobject>
	  </screenshot>
        </figure>

	<para>
	  The first choice in the bubble plot properties allows the
	  user to represent the bubble value based on the area or the
	  diameter of the bubble. The representation of a bubble using
	  the surface is similar to using a log scale since the area
	  is a squared quantity.
        </para>

        <para>
	  The <guilabel>Show negative values</guilabel> property, if
	  the check box is checked, will cause negatives values to be
	  shown with the size of the bubble based on the absolute
	  value of the value and the style of the bubble having a
	  white fill.
        </para>

        <para>
	  The <guilabel>Vary colors by bubble</guilabel>, if the check
          box is checked, will cause each value in a series to be
          displayed with a different fill color instead of coloring
          all the values in a single series with the same color.
        </para>

        <para>
	  The bubbles in a series are scaled relative to each other
          with the maximum value having a default, fixed size and the
          other values being scaled to this maximum bubble. Using this
          spin button, the default size of the maximum bubble can be
          altered. 
        </para>

      </sect3>




      <sect3 id="sect-graphs-elementProperties-plots-pie">
        <title>Pie plots</title>

	<para>
	  Pie plots represent the data values as slices of a circular
	  area, with the central angle of each slice, or wedge,
	  proportional to the size of the value compared to the sum of
	  all the values in the series.
	</para>

        <figure id="fig-graphics-plots-elementProperties-plots-pie">
          <title>The configurable properties of a pie plot.</title>
	  <screenshot>
            <mediaobject> 
	      <imageobject> 
	        <imagedata fileref="figures/graphguru-plot-pie.png"
	                 format="PNG" />
	      </imageobject>
	      <textobject>
	        <para> 
	          This screenshot depicts the properties of a pie plot
	          which can be configured. 
	        </para>
	      </textobject>
	    </mediaobject>
	  </screenshot>
        </figure>

	<para>
	  The slices by default are plotted clockwise starting from
	  the vertical which is considered 0 degrees. The first option
	  allows the user to set a different starting point for the
	  pie series by changing the value in the spin box. The value
	  will increase to 360 degrees and then reset to zero.
        </para>

        <para>
	  Pie plots can be displayed with the slices separated from
	  each other which in certain situations may improve the
	  visual clarity of a pie plot. The second spin button allows
	  the slices to be separated.
        </para>

        <para>
	  The colors of each slice, by default, are all different to
	  allow the easy visual distinction between each slice. Since
	  pie plots only allow a single series to be plotted, there is
	  no need to use color to associate the values from different
	  series. By unchecking this box, all of the slices in a pie
	  chart can be made to follow the color scheme defined in the
	  plot series <guilabel>Style</guilabel> tab. However, if this
	  box is unchecked, the outlines of the slices must be styled
	  with a different color for the slices to be distinguishable.
	</para>

      </sect3>




      <sect3 id="sect-graphs-elementProperties-plots-barCol">
        <title>Bar and Column plots</title>

	<para>
	  Bar and column plots can be displayed with different sized
	  gaps between categories and different overlaps between the
	  values of different series in each category.
	</para>

        <figure id="fig-graphics-plots-elementProperties-plots-">
          <title>The configurable properties of bar and column plots.</title>
	  <screenshot>
            <mediaobject> 
	      <imageobject> 
	        <imagedata fileref="figures/graphguru-plot-barCol.png"
	                 format="PNG" />
	      </imageobject>
	      <textobject>
	        <para> 
	          This screenshot depicts the properties of bar and
	          column plots which can be configured. 
	        </para>
	      </textobject>
	    </mediaobject>
	  </screenshot>
        </figure>

	<para>
	  The <guilabel>Gap</guilabel> describes the separation
	  between the values plotted in each category. By default, the
	  gap between categories is one and half times the width of a
	  bar or a column. This spin button can be used to decrease
	  the gap to zero, so there is no gap between categories, or
	  increase the gap to 500% so the gap is five times the size
	  of a bar or a column.
	</para>

	<para>
	  The <guilabel>Overlap</guilabel> describes the separation
	  between values of the different series in each category. By
	  default these values will be plotted immediately adjacent to
	  each other. This spin button can be lowered to minus 100%
	  which leaves a gap the size of a bar or column between the
	  values of each series. Alternatively, the values can be made
	  to overlap up to 100%, a complete overlap. When values
	  completely overlap, the latter series are plotted on top of
	  the first series and a value may be completely obscured. In
	  this case it may be possible to use partially transparent
	  colors for the different series to allow both values to be
	  visible.  
	</para>

      </sect3>




      <sect3 id="sect-graphs-elementProperties-plots-radar">
        <title>Radar plots</title>

	<para>
	  Radar plots have as many axes as there are categories in
	  each series. 
	</para>

        <figure id="fig-graphics-plots-elementProperties-plots-radar">
          <title>The configurable properties of a radar plot.</title>
	  <screenshot>
            <mediaobject> 
	      <imageobject> 
	        <imagedata fileref="figures/graphguru-plot-radar.png"
	                 format="PNG" />
	      </imageobject>
	      <textobject>
	        <para> 
	          This screenshot depicts the properties of a radar plot
	          which can be configured. 
	        </para>
	      </textobject>
	    </mediaobject>
	  </screenshot>
        </figure>

	<para>
	  By default the axis for the first category is vertical
	  leaving the center point in the upward direction. The first
	  spin box in the radar plot properties allows a user to
	  change this orientation. The spin button can increase from
	  zero degrees to 359 degrees when it will reset to 0.
	</para>

	<note>
	<para>
	  The <guilabel>Vary colors by slice</guilabel> property is
	  probably a mistake which should not be part of radar plot
	  properties. 
	</para>
	</note>


      </sect3>




      <sect3 id="sect-graphs-elementProperties-plots-ring">
        <title>Ring plots</title>

	<para>
	  Ring plots are similar to pie plots but may have an empty
	  center and can be made with multiple series. 
	</para>

        <figure id="fig-graphics-plots-elementProperties-plots-ring">
          <title>The configurable properties of a ring plot.</title>
	  <screenshot>
            <mediaobject> 
	      <imageobject> 
	        <imagedata fileref="figures/graphguru-plot-ring.png"
	                 format="PNG" />
	      </imageobject>
	      <textobject>
	        <para> 
	          This screenshot depicts the properties of a ring plot
	          which can be configured. 
	        </para>
	      </textobject>
	    </mediaobject>
	  </screenshot>
        </figure>

	<para>
	  Like pie plots, ring plots assign values to the slices of a
	  circular area by representing the magnitude of the value by
	  the central angle of the slice, although for ring plots the
	  center of the circular area is empty. Like pie plots, the
	  first slice is plotted starting clockwise from the vertical
	  and this first option can change the beginning point of the
	  first slice's angle.
	</para>

	<para>
	  The slices of a ring plot can also be separated. The
	  <guilabel>Slice Separation</guilabel> option allows a user
	  to determine the proportional size of the gap between
	  slices.
	</para>

	<para>
	  The <guilabel>Center size</guilabel> option determines the
	  size of the hole in the middle of the rings as a fraction of
	  the total radius. The center size can be altered in 5
	  percent increments.
	</para>

	<para>
	  The <guilabel>Vary colors by slice</guilabel> check box
	  allows the user to assign colors either by slices, which is
	  the default, or by series. To use color to distinguish
	  series rather than categories, this button should not be
	  checked. 
	</para>

      </sect3>

    </sect2>






    <sect2 id="sect-graphs-elementProperties-series">
      <title>Data Series</title>

      <para>
        Each plot will have one or more 'series' which organize the
        data values. Each series element has a number of
        properties. The element will have a <guilabel>Style</guilabel>
        tab with which the style of the line and point markers, or the
        area and outline can be set. Each series element will have a
        <guilabel>Data</guilabel> tab in which the name of the series,
        the values used for the series and any labels associated with
        these values can be entered. The data values will generally be
        entered as references to cells on a worksheet which will allow
        the plots to be automatically altered when the values in the
        worksheet change. The series may also have one or more
        <guilabel>Error</guilabel> tabs in which error values can be
        associated to the data value of each element in the series.
      </para>


      <sect3 id="sect-graphs-elementProperties-series-style-line">
        <title>Series line style</title>

	<para>
	  Series in line plots, in some radar plots and in scatter
	  plots will have a style tab in which the graphical style of
	  the lines and point markers can be established.
	</para>

        <figure id="fig-graphics-plots-elementProperties-series-style-line">
          <title>The configurable properties of a line style.</title>
	  <screenshot>
            <mediaobject> 
	      <imageobject> 
	        <imagedata fileref="figures/graphguru-series-style-line.png"
	                 format="PNG" />
	      </imageobject>
	      <textobject>
	        <para> 
	          This screenshot depicts the properties of a line style
	          which can be configured. 
	        </para>
	      </textobject>
	      <caption>
	        <para>
	          The properties of a single value data series include an
	          optional name, a required list of values and an optional
	          list of labels. The name, in this case, is a reference
	          to cell D7 in the first worksheet. The values are the
	          contents of the cells in the range E7:I7. The labels are
	          the contents of the cells in the range E6:I6. Note that
	          there are as many cells in the labels range as in the
	          values range.
	        </para>
	      </caption>
	    </mediaobject>
	  </screenshot>
        </figure>

	<para>
	  The <guilabel>Line</guilabel> properties include the line
	  color and size. The color can be altered in the standard way
	  using the drop down color chooser. The width of the line can
	  be changed with the spin box. A line size of '-1' means that
	  the line will not be plotted. 
	</para>

	<para>
	  The <guilabel>Marker</guilabel> properties determine the
	  style of the graphical symbol which will be plotted for each
	  data value. The first drop down box allows the user to
	  choose between a number of different symbols. The blank
	  symbol indicates that no symbol will be plotted where the
	  data value would be. Each shape will have a fill color, and an
	  outline with both a color and a size. The colors can be
	  changed by clicking on the drop down box and picking one of
	  the given colors or using the color picker to select a new
	  color. The size of the outline can be altered by clicking in
	  the text area and editing the value or by using the spin
	  arrows to increase or decrease the size.
	</para>

      </sect3>




      <sect3 id="sect-graphs-elementProperties-series-style-filled">
        <title>Series filled style</title>

	<para>
	  Series in bubble plots, area plots, bar plots, column plots,
	  filled radar plots, and ring plots will have a
	  <guilabel>Style</guilabel> with fill and outline
	  properties. These properties are the same as those presented
	  for background panels in <xref
	  linkend="sect-graphs-elementProperties-backPanels"/>
	  and are changed in the same way. 
	</para>

        <figure id="fig-graphics-plots-elementProperties-series-style-filled">
          <title>The configurable properties of a filled style.</title>
	  <screenshot>
            <mediaobject> 
	      <imageobject> 
	        <imagedata fileref="figures/graphguru-series-style-filled.png"
	                 format="PNG" />
	      </imageobject>
	      <textobject>
	        <para> 
	          This screenshot depicts the properties of a filled style
	          which can be configured. 
	        </para>
	      </textobject>
	    </mediaobject>
	  </screenshot>
        </figure>

	<para>
	  The <guilabel>Fill</guilabel> properties will determine the
	  character of the inside of the area. The fill type can be
	  none, pattern, gradient, or image, in the same way as the
	  fill of background panels. If images are used for the
	  background, the whole image will be shown and it will be
	  scaled to the size of the area.
	</para>

	<para>
	  The <guilabel>Outline</guilabel> properties will determine
	  the size of the linear element that surrounds the area. The
	  color and size of this outline element can be altered. 
	</para>

      </sect3>




       <sect3 id="sect-graphs-elementProperties-series-data-single">
        <title>Series data: single values</title>

	<para>
	  The <guilabel>Data</guilabel> tab allows the user to
	  configure the data contents of the series. Some of these
	  data contents are optional, as is indicated by the
	  parentheses around the label. At the minimum one set of
	  numerical quantities will be required.
	</para>

	<para>
	  The entry boxes in the <guilabel>Data</guilabel> tab can be
	  filled in several ways. The data can be a static value or
	  array such as a sting literal, "SeriesName", or a group of
	  values, <literal>{12.05, 73.02, 128.89}</literal>. Note that
	  the separator between elements in the array will depend on
	  the locale since the glyph between whole numbers and decimal
	  fractions differs around the world. Alternatively, the value
	  of an entry box can be the reference to a cell or to a
	  range. This reference can either be typed into the entry box
	  or can be entered by clicking in the entry box text area and
	  then selecting the range on the worksheet. Finally, the
	  value in the entry box can be an expression, such as
	  <literal>sin({120, 982, 140})</literal>.
	</para>

	<para>
	  Single series involve the simplest data. They may have an
	  overall name, must have a list of values, and may have a
	  list of names, with as many names as there are numbers in
	  the values list, which will act as category names. For plot
	  types with more than one single list series, the label names
	  will be shared between all the series.
	</para>

        <figure id="fig-graphics-plots-elementProperties-series-data-">
          <title>The configurable properties of single value data series.</title>
	  <screenshot>
            <mediaobject> 
	      <imageobject> 
	        <imagedata fileref="figures/graphguru-series-data-single.png"
	                 format="PNG" />
	      </imageobject>
	      <textobject>
	        <para> 
	          This screenshot depicts the properties of a single
	          value data series 
	          which can be configured. 
	        </para>
	      </textobject>
	    </mediaobject>
	  </screenshot>
        </figure>

	<para>
	  The <guilabel>Name</guilabel> property is a single string
	  which will give a tag to the series itself. A name is not
	  required. This name will be used in the Graph Guru to name
	  the series and may be used in a chart legend to describe the
	  series.
	</para>

	<para>
	  The <guilabel>Values</guilabel> property must contain a list
	  of numeric quantities. A list of values is required. The
	  values can be described either directly as a static array,
	  described through a reference to a cell range with numeric
	  values, or described through an expression which results in
	  the list of quantities.
	</para>

 	<para>
	  The <guilabel>Labels</guilabel> property describes the names
	  of the categories. This property is not required. must be a list of
	  text elements, with as many elements as there are quantities
	  in the list of values. These elements will provide the
	  elements in the legend for pie and ring plots. For line,
	  area, bar and column plots, the labels will provide the
	  category names for the axis with categories. 
	</para>

 	<para>
	  The <guilabel>Show in Legend</guilabel> property determines
	  if this series will be shown in the legend if a legend is
	  added to the chart. It is sometimes useful to exclude
	  certain series from the legend. If the box is checked, the
	  series will be included in any legend displayed in the
	  chart; if the box is not checked, the series will not be
	  displayed in the legend. The box can be unchecked by placing
	  the mouse pointer over the box and clicking with the primary
	  mouse button.
	</para>

    </sect3>





      <sect3 id="sect-graphs-elementProperties-series-data-xy">
        <title>Series data: X and Y values</title>

	<para>
	  Series with dual data values allow plots to be constructed
	  in which one value is plotted against the other. XY scatter
	  plots require this type of data.
	</para>

        <figure id="fig-graphics-plots-elementProperties-series-data-xy">
          <title>The configurable properties of dual value data series.</title>
	  <screenshot>
            <mediaobject> 
	      <imageobject> 
	        <imagedata fileref="figures/graphguru-series-data-xy.png"
	                 format="PNG" />
	      </imageobject>
	      <textobject>
	        <para> 
	          This screenshot depicts the properties of data
	          series with two values, an x and a y,
	          which can be configured. 
	        </para>
	      </textobject>
	      <caption>
	        <para>
	          Dual data series require two sets of values, an X list
	          and a Y list.
	        </para>
	      </caption>
	    </mediaobject>
	  </screenshot>
        </figure>

	<para>
	  The <guilabel>Name</guilabel> property is a single text
	  element that will name the series in the graph guru and in
	  any legend in the chart.
	</para>

	<para>
	  The <guilabel>X</guilabel> property is a list of
	  quantitative values that will provide the horizontal
	  positioning of each element. This list is required.
	</para>

	<para>
	  The <guilabel>Y</guilabel> property is a list of
	  quantitative values that will provide the vertical
	  positioning of each element. This list is required and must
	  have the same number of elements as the list of X values. 
	</para>

      </sect3>




      <sect3 id="sect-graphs-elementProperties-series-data-bubble">
        <title>Series data: bubble values</title>

	<para>
	  Bubble series are simple extensions of the XY series to
	  include a third data value, often called W, which will
	  determine the size of the bubble.
	</para>

        <figure id="fig-graphics-plots-elementProperties-series-data-bubble">
          <title>The configurable properties of bubble data series.</title>
	  <screenshot>
            <mediaobject> 
	      <imageobject> 
	        <imagedata fileref="figures/graphguru-series-data-bubble.png"
	                 format="PNG" />
	      </imageobject>
	      <textobject>
	        <para> 
	          This screenshot depicts the properties of a bubble
	  data series with three values
	          which can be configured. 
	        </para>
	      </textobject>
	    </mediaobject>
	  </screenshot>
        </figure>

	<para>
	  The <guilabel>Name</guilabel> property is a single text
	  element that will name the series in the graph guru and in
	  any legend in the chart.
	</para>

	<para>
	  The <guilabel>X</guilabel> property is a list of
	  quantitative values that will provide the horizontal
	  positioning of each element. This list is required.
	</para>

	<para>
	  The <guilabel>Y</guilabel> property is a list of
	  quantitative values that will provide the vertical
	  positioning of each element. This list is required and must
	  have the same number of elements as the list of X values. 
	</para>

	<para>
	  The <guilabel>Bubble</guilabel> property is a list of
	  quantitative values that will provide the size of the
	  bubbles associated to each element. This list is required
	  and must have the same number of elements as the lists of X
	  and of Y values.
	</para>

      </sect3>



     <sect3 id="sect-graphs-elementProperties-series-error">
        <title>Series error values</title>

	<para>
	  Several plot types allow the plotting of error values using
	  whisker plots. The series in these plot types will have
	  extra tabs allowing the whisker positions to be
	  listed. Line, bar, column and area plots allow an error plot
	  to bracket the plotted quantitative value in the direction
	  of the quantitative axis. XY scatter plots and bubble plots
	  allow whiskers in both directions.
	</para>

        <figure id="fig-graphics-plots-elementProperties-series-error">
          <title>The configurable properties of data series error values.</title>
	  <screenshot>
            <mediaobject> 
	      <imageobject> 
	        <imagedata fileref="figures/graphguru-series-error.png"
	                 format="PNG" />
	      </imageobject>
	      <textobject>
	        <para> 
	          This screenshot depicts the properties of the error
	          values in a data series
	          which can be configured. 
	        </para>
	      </textobject>
	    </mediaobject>
	  </screenshot>
        </figure>

	<para>
	  The <guilabel>Error Category</guilabel> includes several
	  different categories which can be selected by clicking on
	  the drop down box and dragging the mouse pointer onto the
	  appropriate entry. If the error category is set to "none",
	  no error bars will be plotted. If the category is set to
	  "absolute" the values in the error lists will be considered
	  to be in the same units as the axis. If the category is set
	  to "relative", the values in the error list are assumed to
	  be a fraction of the total of each value. If the category is
	  set to "percent", the values in the error list are assumed
	  to be 1/100 th of the fraction of the total of each
	  value. Note that if the cells in the worksheet are already
	  set to the percent format, they should be incorporated as
	  "relative" errors.
	</para>

	<para>
	  The <guilabel>Style</guilabel> properties alter the
	  appearance of the error whiskers. The
	  <guilabel>Display</guilabel> property can be used to prevent
	  the display of any whiskers, to allow
	  only upper or lower whiskers, or to display both. The
	  <guilabel>Width</guilabel> property alters the width of
	  the outer marker of the whisker. The <guilabel>Line
	  width</guilabel> property alters the size of the
	  whiskers. The color box selects the color of the line used
	  to draw the whiskers.
	</para>

	<para>
	  The <guilabel>Values</guilabel> properties describe the lists
	  of quantitative values which will be used for the
	  whiskers. These lists are required if an error is to be
	  displayed and the lists must have as many elements as were
	  in the list of data "Values". The positive (+) list
	  quantifies either only the upper error values if the lower
	  values are not displayed or the negative list is
	  defined. The positive list can also be used for both error
	  values if the errors are symmetrical. The negative (-) list
	  quantifies the lower whisker.
	</para>

      </sect3>

    </sect2>

  </sect1>






  <sect1 id="sect-graphs-preselect">
    <title>Pre-Selecting Data</title>

    <para>
      This section is not yet written.
    </para>

  </sect1>

