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+'\"
+'\" Copyright 1991-1998 by Bell Labs Innovations for Lucent Technologies.
+'\"
+'\" Permission to use, copy, modify, and distribute this software and its
+'\" documentation for any purpose and without fee is hereby granted, provided
+'\" that the above copyright notice appear in all copies and that both that the
+'\" copyright notice and warranty disclaimer appear in supporting documentation,
+'\" and that the names of Lucent Technologies any of their entities not be used
+'\" in advertising or publicity pertaining to distribution of the software
+'\" without specific, written prior permission.
+'\"
+'\" Lucent Technologies disclaims all warranties with regard to this software,
+'\" including all implied warranties of merchantability and fitness.  In no event
+'\" shall Lucent Technologies be liable for any special, indirect or
+'\" consequential damages or any damages whatsoever resulting from loss of use,
+'\" data or profits, whether in an action of contract, negligence or other
+'\" tortuous action, arising out of or in connection with the use or performance
+'\" of this software.  
+'\"
+'\" Barchart widget created by Sani Nassif and George Howlett.
+'\"
+.so man.macros
+.TH barchart n BLT_VERSION BLT "BLT Built-In Commands"
+.BS
+'\" Note:  do not modify the .SH NAME line immediately below!
+.SH NAME
+barchart \-  Bar chart for plotting X-Y coordinate data.
+.SH SYNOPSIS
+\fBbarchart\fI \fIpathName \fR?\fIoption value\fR?...
+.BE
+.SH DESCRIPTION
+The \fBbarchart\fR command creates a bar chart for plotting
+two-dimensional data (X-Y coordinates). A bar chart is a graphic means
+of comparing numbers by displaying bars of lengths proportional to the
+y-coordinates of the points they represented.  The bar chart has many
+configurable components: coordinate axes, elements, legend, grid
+lines, cross hairs, etc.  They allow you to customize the look and
+feel of the graph.
+.SH INTRODUCTION
+The \fBbarchart\fR command creates a new window for plotting
+two-dimensional data (X-Y coordinates), using bars of
+various lengths to represent the data points.  The bars are drawn in a
+rectangular area displayed in the center of the new window.  This is the
+\fIplotting area\fR.  The coordinate axes are drawn in
+the margins surrounding the plotting area.  By default, the legend is
+drawn in the right margin.  The title is displayed in top margin.
+.PP
+A \fBbarchart\fR widget has several configurable components:
+coordinate axes, data elements, legend, grid, cross hairs, pens,
+postscript, and annotation markers.  Each component can be queried or
+modified.
+.TP 1i
+\f(CWaxis\fR 
+
+Up to four coordinate axes (two X\-coordinate and two Y\-coordinate
+axes) can be displayed, but you can create and use any number of
+axes. Axes control what region of data is displayed and how the data
+is scaled. Each axis consists of the axis line, title, major and minor
+ticks, and tick labels. Tick labels display the value at each major
+tick.
+.TP 1i
+\f(CWcrosshairs\fR 
+Cross hairs are used to position the mouse pointer relative to the X
+and Y coordinate axes. Two perpendicular lines, intersecting at the
+current location of the mouse, extend across the plotting area to the
+coordinate axes.
+.TP 1i
+\f(CWelement\fR 
+An element represents a set of data to be plotted.  It contains an x
+and y vector of values representing the data points.  Each
+data point is displayed as a bar where the length of the bar is
+proportional to the ordinate (Y-coordinate) of the data point.
+The appearance of the bar, such as its color, stipple, or relief
+is configurable.
+.sp
+A special case exists when two or more data points have the same
+abscissa (X-coordinate).  By default, the bars are overlayed, one on
+top of the other.  The bars are drawn in the order of the element
+display list.  But you can also configure the bars to be displayed in
+two other ways.  They may be displayed as a stack, where each bar
+(with the same abscissa) is stacked on the previous.  Or they can be
+drawn side-by-side as thin bars.  The width of each bar is a function
+of the number of data points with the same abscissa.
+.TP 1i
+\f(CWgrid\fR
+Extends the major and minor ticks of the X\-axis and/or Y\-axis across the 
+plotting area. 
+.TP 1i
+\f(CWlegend\fR 
+The legend displays the name and symbol of each data element. 
+The legend can be drawn in any margin or in the plotting area.
+.TP 1i
+\f(CWmarker\fR
+Markers are used annotate or highlight areas of the graph. For
+example, you could use a text marker to label a particular data
+point. Markers come in various forms: text strings, bitmaps, connected
+line segments, images, polygons, or embedded widgets.
+.TP 1i
+\f(CWpen\fR 
+Pens define attributes for elements.  Data elements use pens to
+specify how they should be drawn.  A data element may use many pens at
+once.  Here the particular pen used for a data point is determined
+from each element's weight vector (see the element's \fB\-weight\fR
+and \fB\-style\fR options).
+.TP 1i
+\f(CWpostscript\fR
+The widget can generate encapsulated PostScript output. This component
+has several options to configure how the PostScript is generated.
+.SH SYNTAX
+.DS
+\fBbarchart \fIpathName \fR?\fIoption value\fR?...
+.DE
+The \fBbarchart\fR command creates a new window \fIpathName\fR and makes
+it into a \fBbarchart\fR widget.  At the time this command is invoked, there
+must not exist a window named \fIpathName\fR, but \fIpathName\fR's
+parent must exist.  Additional options may be specified on the
+command line or in the option database to configure aspects of the
+graph such as its colors and font.  See the \fBconfigure\fR operation
+below for the exact details about what \fIoption\fR and \fIvalue\fR
+pairs are valid.
+.PP
+If successful, \fBbarchart\fR returns the path name of the widget.  It
+also creates a new Tcl command by the same name.  You can use this
+command to invoke various operations that query or modify the graph.
+The general form is:
+.DS
+\fIpathName \fIoperation\fR \fR?\fIarg\fR?...
+.DE
+Both \fIoperation\fR and its arguments determine the exact behavior of
+the command.  The operations available for the graph are described in 
+the 
+.SB "BARCHART OPERATIONS"
+section.
+.PP
+The command can also be used to access components of the graph.
+.DS
+\fIpathName component operation\fR ?\fIarg\fR?...
+.DE
+The operation, now located after the name of the component, is the
+function to be performed on that component. Each component has its own
+set of operations that manipulate that component.  They will be
+described below in their own sections.
+.SH EXAMPLE
+The \fBbarchart\fR command creates a new bar chart.  
+.CS
+# Create a new bar chart.  Plotting area is black.
+barchart .b -plotbackground black
+.CE
+A new Tcl command \f(CW.b\fR is created.  This command can be used
+to query and modify the bar chart.  For
+example, to change the title of the graph to "My Plot", you use the
+new command and the \fBconfigure\fR operation.
+.CS
+# Change the title.
+\&.b configure -title "My Plot"
+.CE
+To add data elements, you use the command and the \fBelement\fR component.
+.CS
+# Create a new element named "e1"
+\&.b element create e1 \\
+	-xdata { 1 2 3 4 5 6 7 8 9 10 } \\
+	-ydata { 26.18 50.46 72.85 93.31 111.86 128.47 143.14 
+		155.85 166.60 175.38 }
+.CE
+The element's X-Y coordinates are specified using lists of
+numbers.  Alternately, BLT vectors could be used to hold the X-Y
+coordinates.
+.CS
+# Create two vectors and add them to the barchart.
+vector xVector yVector
+xVector set { 1 2 3 4 5 6 7 8 9 10 }
+yVector set { 26.18 50.46 72.85 93.31 111.86 128.47 143.14 155.85 
+	166.60 175.38 }
+\&n.b element create e1 -xdata xVector -ydata yVector
+.CE
+The advantage of using vectors is that when you modify one, the graph
+is automatically redrawn to reflect the new values.
+.CS
+# Change the y coordinate of the first point.
+set yVector(0) 25.18
+.CE
+An element named \f(CWe1\fR is now created in \f(CW.b\fR.  It 
+is automatically added to the display list of elements.  You can
+use this list to control in what order elements are displayed.
+To query or reset the element display list, you use the element's 
+\fBshow\fR operation.
+.CS
+# Get the current display list 
+set elemList [.b element show]
+# Remove the first element so it won't be displayed.
+\&.b element show [lrange $elemList 0 end]
+.CE
+The element will be displayed by as many bars as there are data points
+(in this case there are ten).  The bars will be drawn centered at the
+x-coordinate of the data point.  All the bars will have the same
+attributes (colors, stipple, etc).  The width of each bar is by
+default one unit.  You can change this with using the \fB\-barwidth\fR
+option.
+.CS
+# Change the scale of the x-coordinate data 
+xVector set { 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 }
+# Make sure we change the bar width too.
+\&.b configure -barwidth 0.2
+.CE
+The height of each bar is proportional to the ordinate (Y-coordinate)
+of the data point.
+.PP
+If two or more data points have the same abscissa (X-coordinate
+value), the bars representing those data points may be drawn in 
+various ways.
+The default is to overlay the bars, one on top of the other.
+The ordering is determined from the of element display list.  If
+the stacked mode is selected (using the \fB\-barmode\fR configuration
+option), the bars are stacked, each bar above the previous.
+.CS
+# Display the elements as stacked.
+\&.b configure -barmode stacked
+.CE
+If the aligned mode is selected, the bars having the same
+x-coordinates are displayed side by side.  The width of each bar is a
+fraction of its normal width, based upon the number of bars with the
+same x-coordinate.
+.CS
+# Display the elements side-by-side.
+\&.b configure -barmode aligned
+.CE
+By default, the element's label in the legend will be also
+\f(CWe1\fR.  You can change the label, or specify no legend entry,
+again using the element's \fBconfigure\fR operation.
+.CS
+# Don't display "e1" in the legend.
+\&.b element configure e1 -label ""
+.CE
+You can configure more than just the element's label.  An element has
+many attributes such as stipple, foreground and background colors,
+relief, etc.
+.CS
+\&.b element configure e1 -fg red -bg pink \\
+	-stipple gray50
+.CE
+Four coordinate axes are automatically created: \f(CWx\fR, \f(CWx2\fR,
+\f(CWy\fR, and \f(CWy2\fR.  And by default, elements are mapped onto the
+axes \f(CWx\fR and \f(CWy\fR.  This can be changed with the \fB\-mapx\fR
+and \fB\-mapy\fR options.
+.CS
+# Map "e1" on the alternate y axis "y2".
+\&.b element configure e1 -mapy y2
+.CE
+Axes can be configured in many ways too.  For example, you change the
+scale of the Y\-axis from linear to log using the \fBaxis\fR component.
+.CS
+# Y-axis is log scale.
+\&.b axis configure y -logscale yes
+.CE
+One important way axes are used is to zoom in on a particular data
+region.  Zooming is done by simply specifying new axis limits using
+the \fB\-min\fR and \fB\-max\fR configuration options.
+.CS
+\&.b axis configure x \-min 1.0 \-max 1.5
+\&.b axis configure y \-min 12.0 \-max 55.15
+.CE
+To zoom interactively, you link the\fBaxis configure\fR operations with
+some user interaction (such as pressing the mouse button), using the
+\fBbind\fR command.  To convert between screen and graph coordinates,
+use the \fBinvtransform\fR operation.
+.CS
+# Click the button to set a new minimum 
+bind .b <ButtonPress-1> { 
+    %W axis configure x \-min [%W axis invtransform x %x]
+    %W axis configure x \-min [%W axis invtransform x %y]
+}
+.CE
+By default, the limits of the axis are determined from data values.
+To reset back to the default limits, set the \fB\-min\fR and
+\fB\-max\fR options to the empty value.
+.CS
+# Reset the axes to autoscale again.
+\&.b axis configure x \-min {} \-max {}
+\&.b axis configure y \-min {} \-max {}
+.CE
+By default, the legend is drawn in the right margin.  You can
+change this or any legend configuration options using the
+\fBlegend\fR component.
+.CS
+# Configure the legend font, color, and relief
+\&.b legend configure -position left -relief raised \\
+	-font fixed -fg blue
+.CE
+To prevent the legend from being displayed, turn on the \fB\-hide\fR
+option.
+.CS
+# Don't display the legend.
+\&.b legend configure \-hide yes\fR
+.CE
+The \fBbarchart\fR has simple drawing procedures called markers.  They can be
+used to highlight or annotate data in the graph. The types of markers
+available are bitmaps, polygons, lines, or windows.  Markers can be
+used, for example, to mark or brush points.  For example there may be
+a line marker which indicates some low-water value.  Markers are created
+using the \fBmarker\fR operation.
+.CS
+# Create a line represent the low water mark at 10.0
+\&.b marker create line -name "low_water" \\
+	-coords { -Inf 10.0 Inf 10.0 } \\
+	-dashes { 2 4 2 } -fg red -bg blue 
+.CE
+This creates a line marker named \f(CWlow_water\fR.  It will display a
+horizontal line stretching across the plotting area at the
+y-coordinate 10.0.  The coordinates "-Inf" and "Inf" indicate the
+relative minimum and maximum of the axis (in this case the x-axis).  By
+default, markers are drawn last, on top of the bars.  You can change this
+with the \fB\-under\fR option.
+.CS
+# Draw the marker before elements are drawn.
+\&.b marker configure low_water -under yes
+.CE
+You can add cross hairs or grid lines using the \fBcrosshairs\fR and
+\fBgrid\fR components.
+.CS
+# Display both cross hairs and grid lines.
+\&.b crosshairs configure -hide no -color red
+\&.b grid configure -hide no -dashes { 2 2 }
+.CE
+Finally, to get hardcopy of the graph, use the \fBpostscript\fR
+component.
+.CS
+# Print the bar chart into file "file.ps"
+\&.b postscript output file.ps -maxpect yes -decorations no
+.CE
+This generates a file \f(CWfile.ps\fR containing the encapsulated
+PostScript of the graph.  The option \fB\-maxpect\fR says to scale the
+plot to the size of the page.  Turning off the \fB\-decorations\fR
+option denotes that no borders or color backgrounds should be
+drawn (i.e. the background of the margins, legend, and plotting
+area will be white).
+.SH SYNTAX
+.DS
+\fBbarchart \fIpathName \fR?\fIoption value\fR?...
+.DE
+The \fBbarchart\fR command creates a new window \fIpathName\fR and makes
+it into a barchart widget.  At the time this command is invoked, there
+must not exist a window named \fIpathName\fR, but \fIpathName\fR's
+parent must exist.  Additional options may may be specified on the
+command line or in the option database to configure aspects of the
+bar chart such as its colors and font.  See the \fBconfigure\fR operation
+below for the exact details as to what \fIoption\fR and \fIvalue\fR
+pairs are valid.
+.PP
+If successful, \fBbarchart\fR returns \fIpathName\fR. It also creates a
+new Tcl command \fIpathName\fR.  This command may be used to invoke
+various operations to query or modify the bar chart.  It has the general
+form:
+.DS
+\fIpathName \fIoperation\fR \fR?\fIarg\fR?...
+.DE
+Both \fIoperation\fR and its arguments determine the exact behavior of
+the command.  The operations available for the bar chart are described in
+the following section.
+.SH "BARCHART OPERATIONS"
+.TP
+\fIpathName \fBbar \fIelemName \fR?\fIoption value\fR?...
+Creates a new barchart element \fIelemName\fR.  It's an
+error if an element \fIelemName\fR already exists.  
+See the manual for \fBbarchart\fR for details about
+what \fIoption\fR and \fIvalue\fR pairs are valid.
+.TP
+\fIpathName \fBcget\fR \fIoption\fR
+Returns the current value of the configuration option given by
+\fIoption\fR.  \fIOption\fR may be any option described
+below for the \fBconfigure\fR operation.
+.TP
+\fIpathName \fBconfigure \fR?\fIoption value\fR?...
+Queries or modifies the configuration options of the graph.  If
+\fIoption\fR isn't specified, a list describing the current
+options for \fIpathName\fR is returned.  If \fIoption\fR is specified,
+but not \fIvalue\fR, then a list describing \fIoption\fR is returned.
+If one or more \fIoption\fR and \fIvalue\fR pairs are specified, then
+for each pair, the option \fIoption\fR is set to \fIvalue\fR.
+The following options are valid.
+.RS
+.TP
+\fB\-background \fIcolor\fR
+Sets the background color. This includes the margins and
+legend, but not the plotting area.
+.TP
+\fB\-barmode \fImode\fR 
+Indicates how related bar elements will be drawn.  Related elements
+have data points with the same abscissas (X-coordinates). \fIMode\fR
+indicates how those segments should be drawn. \fIMode\fR can be
+\f(CWinfront\fR, \f(CWaligned\fR, \f(CWoverlap\fR, or \f(CWstacked\fR.
+The default mode is \f(CWinfront\fR.
+.RS
+.TP 1i
+\f(CWinfront\fR
+Each successive segment is drawn in front of the previous. 
+.TP 1i
+\f(CWstacked\fR
+Each successive segment is stacked vertically on top of the previous.  
+.TP 1i
+\f(CWaligned\fR
+Segments is displayed aligned from right-to-left.  
+.TP 1i
+\f(CWoverlap\fR
+Like \f(CWaligned\fR but segments slightly overlap each other.  
+.RE
+.TP
+\fB\-barwidth \fIvalue\fR 
+Specifies the width of the bars.  This value can be overrided by the
+individual elements using their \fB\-barwidth\fR configuration option.
+\fIValue\fR is the width in terms of graph-coordinates.  The
+default width is \f(CW1.0\fR.
+.TP
+\fB\-borderwidth \fIpixels\fR
+Sets the width of the 3\-D border around the outside edge of the widget.  The
+\fB\-relief\fR option determines if the border is to be drawn.  The
+default is \f(CW2\fR.
+.TP
+\fB\-bottommargin \fIpixels\fR
+Specifies the size of the margin below the X\-coordinate axis.  If
+\fIpixels\fR is \f(CW0\fR, the size of the margin is selected automatically.
+The default is \f(CW0\fR.
+.TP
+\fB\-bufferelements \fIboolean\fR
+Indicates whether an internal pixmap to buffer the display of data
+elements should be used.  If \fIboolean\fR is true, data elements are
+drawn to an internal pixmap.  This option is especially useful when
+the graph is redrawn frequently while the remains data unchanged (for
+example, moving a marker across the plot).  See the
+.SB "SPEED TIPS"
+section.
+The default is \f(CW1\fR.
+.TP
+\fB\-cursor \fIcursor\fR
+Specifies the widget's cursor.  The default cursor is \f(CWcrosshair\fR.
+.TP
+\fB\-font \fIfontName\fR 
+Specifies the font of the graph title. The default is
+\f(CW*-Helvetica-Bold-R-Normal-*-18-180-*\fR.
+.TP
+\fB\-halo \fIpixels\fR 
+Specifies a maximum distance to consider when searching for the
+closest data point (see the element's \fBclosest\fR operation below).
+Data points further than \fIpixels\fR away are ignored.  The default is
+\f(CW0.5i\fR.
+.TP
+\fB\-height \fIpixels\fR
+Specifies the requested height of widget.  The default is
+\f(CW4i\fR.
+.TP
+\fB\-invertxy \fIboolean\fR
+Indicates whether the placement X\-axis and Y\-axis should be inverted.  If
+\fIboolean\fR is true, the X and Y axes are swapped.  The default is
+\f(CW0\fR.
+.TP
+\fB\-justify \fIjustify\fR
+Specifies how the title should be justified.  This matters only when
+the title contains more than one line of text. \fIJustify\fR must be
+\f(CWleft\fR, \f(CWright\fR, or \f(CWcenter\fR.  The default is
+\f(CWcenter\fR.
+.TP
+\fB\-leftmargin \fIpixels\fR
+Sets the size of the margin from the left edge of the window to 
+the Y\-coordinate axis.  If \fIpixels\fR is \f(CW0\fR, the size is
+calculated automatically.  The default is \f(CW0\fR.
+.TP
+\fB\-plotbackground \fIcolor\fR
+Specifies the background color of the plotting area.  The default is
+\f(CWwhite\fR.
+.TP
+\fB\-plotborderwidth \fIpixels\fR
+Sets the width of the 3-D border around the plotting area.  The
+\fB\-plotrelief\fR option determines if a border is drawn.  The
+default is \f(CW2\fR.
+.TP
+\fB\-plotpadx \fIpad\fR
+Sets the amount of padding to be added to the left and right sides of
+the plotting area.  \fIPad\fR can be a list of one or two screen
+distances.  If \fIpad\fR has two elements, the left side of the
+plotting area entry is padded by the first distance and the right side
+by the second.  If \fIpad\fR is just one distance, both the left and
+right sides are padded evenly.  The default is \f(CW8\fR.
+.TP
+\fB\-plotpady \fIpad\fR
+Sets the amount of padding to be added to the top and bottom of the
+plotting area.  \fIPad\fR can be a list of one or two screen
+distances.  If \fIpad\fR has two elements, the top of the plotting
+area is padded by the first distance and the bottom by the second.  If
+\fIpad\fR is just one distance, both the top and bottom are padded
+evenly.  The default is \f(CW8\fR.
+.TP
+\fB\-plotrelief \fIrelief\fR
+Specifies the 3-D effect for the plotting area.  \fIRelief\fR
+specifies how the interior of the plotting area should appear relative
+to rest of the graph; for example, \f(CWraised\fR means the plot should
+appear to protrude from the graph, relative to the surface of the
+graph.  The default is \f(CWsunken\fR.
+.TP
+\fB\-relief \fIrelief\fR
+Specifies the 3-D effect for the barchart widget.  \fIRelief\fR
+specifies how the graph should appear relative to widget it is packed
+into; for example, \f(CWraised\fR means the graph should
+appear to protrude.  The default is \f(CWflat\fR.
+.TP
+\fB\-rightmargin \fIpixels\fR
+Sets the size of margin from the plotting area to the right edge of
+the window.  By default, the legend is drawn in this margin.  If
+\fIpixels\fR is than 1, the margin size is selected automatically.
+.TP
+\fB\-takefocus\fR \fIfocus\fR 
+Provides information used when moving the focus from window to window
+via keyboard traversal (e.g., Tab and Shift-Tab).  If \fIfocus\fR is
+\f(CW0\fR, this means that this window should be skipped entirely during
+keyboard traversal.  \f(CW1\fR means that the this window should always
+receive the input focus.  An empty value means that the traversal
+scripts make the decision whether to focus on the window.
+The default is \f(CW""\fR.
+.TP
+\fB\-tile \fIimage\fR 
+Specifies a tiled background for the widget.  If \fIimage\fR isn't
+\f(CW""\fR, the background is tiled using \fIimage\fR.
+Otherwise, the normal background color is drawn (see the
+\fB\-background\fR option).  \fIImage\fR must be an image created
+using the Tk \fBimage\fR command.  The default is \f(CW""\fR.
+.TP
+\fB\-title \fItext\fR 
+Sets the title to \fItext\fR. If \fItext\fR is \f(CW""\fR,
+no title will be displayed.
+.TP
+\fB\-topmargin \fIpixels\fR
+Specifies the size of the margin above the x2 axis.  If \fIpixels\fR
+is \f(CW0\fR, the margin size is calculated automatically.
+.TP
+\fB\-width \fIpixels\fR
+Specifies the requested width of the widget.  The default is
+\f(CW5i\fR.
+.RE
+.TP
+\fIpathName \fBcrosshairs \fIoperation \fR?\fIarg\fR?
+See the 
+.SB "CROSSHAIRS COMPONENT"
+section.
+.TP
+\fIpathName \fBelement \fIoperation \fR?\fIarg\fR?...
+See the 
+.SB "ELEMENT COMPONENTS"
+section.
+.TP
+\fIpathName \fBextents \fIitem\fR 
+Returns the size of a particular item in the graph.  \fIItem\fR must
+be either \f(CWleftmargin\fR, \f(CWrightmargin\fR, \f(CWtopmargin\fR,
+\f(CWbottommargin\fR, \f(CWplotwidth\fR, or \f(CWplotheight\fR.
+.TP
+\fIpathName \fBgrid \fIoperation \fR?\fIarg\fR?...
+See the 
+.SB "GRID COMPONENT"
+section.
+.TP
+\fIpathName \fBinvtransform \fIwinX winY\fR 
+Performs an inverse coordinate transformation, mapping window
+coordinates back to graph-coordinates, using the standard X\-axis and Y\-axis.
+Returns a list of containing the X-Y graph-coordinates.
+.TP
+\fIpathName \fBinside \fIx y\fR
+Returns \f(CW1\fR is the designated screen-coordinate (\fIx\fR and \fIy\fR)
+is inside the plotting area and \f(CW0\fR otherwise.
+.TP
+\fIpathName \fBlegend \fIoperation \fR?\fIarg\fR?...
+See the 
+.SB "LEGEND COMPONENT"
+section.
+.TP
+\fIpathName \fBline\fB operation arg\fR...
+The operation is the same as \fBelement\fR.
+.TP
+\fIpathName \fBmarker \fIoperation \fR?\fIarg\fR?...
+See the 
+.SB "MARKER COMPONENTS"
+section.
+.TP
+\fIpathName\fR \fBmetafile\fR ?\fIfileName\fR?
+\fIThis operation is for Window platforms only\fR.  
+Creates a Windows enhanced metafile of the barchart.
+If present, \fIfileName\fR is the file name of the new metafile.
+Otherwise, the metafile is automatically added to the clipboard.
+.TP
+\fIpathName \fBpostscript \fIoperation \fR?\fIarg\fR?...
+See the 
+.SB "POSTSCRIPT COMPONENT"
+section.
+.TP
+\fIpathName \fBsnap \fIphotoName\fR
+Takes a snapshot of the graph and stores the contents in the photo
+image \fIphotoName\fR.  \fIPhotoName\fR is the name of a Tk photo
+image that must already exist.
+.TP
+\fIpathName \fBtransform \fIx y\fR 
+Performs a coordinate transformation, mapping graph-coordinates to
+window coordinates, using the standard X\-axis and Y\-axis.
+Returns a list containing the X\-Y screen-coordinates.
+.TP
+\fIpathName \fBxaxis \fIoperation\fR ?\fIarg\fR?...
+.TP
+\fIpathName \fBx2axis \fIoperation\fR ?\fIarg\fR?... 
+.TP
+\fIpathName \fByaxis \fIoperation\fR ?\fIarg\fR?... 
+.TP
+\fIpathName \fBy2axis \fIoperation\fR ?\fIarg\fR?... 
+See the 
+.SB "AXIS COMPONENTS"
+section.
+.SH "BARCHART COMPONENTS"
+A graph is composed of several components: coordinate axes, data
+elements, legend, grid, cross hairs, postscript, and annotation
+markers. Instead of one big set of configuration options and
+operations, the graph is partitioned, where each component has its own
+configuration options and operations that specifically control that
+aspect or part of the graph. 
+.SS "AXIS COMPONENTS"
+Four coordinate axes are automatically created: two X\-coordinate axes
+(\f(CWx\fR and \f(CWx2\fR) and two Y\-coordinate axes (\f(CWy\fR, and
+\f(CWy2\fR).  By default, the axis \f(CWx\fR is located in the bottom
+margin, \f(CWy\fR in the left margin, \f(CWx2\fR in the top margin, and
+\f(CWy2\fR in the right margin.
+.PP
+An axis consists of the axis line, title, major and minor ticks, and
+tick labels.  Major ticks are drawn at uniform intervals along the
+axis.  Each tick is labeled with its coordinate value.  Minor ticks
+are drawn at uniform intervals within major ticks.  
+.PP
+The range of the axis controls what region of data is plotted.
+Data points outside the minimum and maximum limits of the axis are
+not plotted.  By default, the minimum and maximum limits are
+determined from the data, but you can reset either limit.
+.PP
+You can create and use several axes. To create an axis, invoke
+the axis component and its create operation.
+.CS
+# Create a new axis called "temperature"
+\&.b axis create temperature
+.CE
+You map data elements to an axis using the element's \-mapy and \-mapx
+configuration options. They specify the coordinate axes an element
+is mapped onto.
+.CS
+# Now map the temperature data to this axis.
+\&.b element create "temp" \-xdata $x \-ydata $tempData \\
+    \-mapy temperature
+.CE
+While you can have many axes, only four axes can be displayed
+simultaneously.  They are drawn in each of the margins surrounding
+the plotting area.  The axes \f(CWx\fR and \f(CWy\fR are drawn in the
+bottom and left margins. The axes \f(CWx2\fR and \f(CWy2\fR are drawn in
+top and right margins.  Only \f(CWx\fR and \f(CWy\fR are shown by
+default. Note that the axes can have different scales.
+.PP
+To display a different axis, you invoke one of the following
+components: \fBxaxis\fR, \fByaxis\fR, \fBx2axis\fR, and \fBy2axis\fR.
+The \fBuse\fR operation designates the axis to be drawn in the
+corresponding margin: \fBxaxis\fR in the bottom, \fByaxis\fR in the left, 
+\fBx2axis\fR in the top, and \fBy2axis\fR in the right.
+.CS
+# Display the axis temperature in the left margin.
+\&.b yaxis use temperature
+.CE
+.PP
+You can configure axes in many ways. The axis scale can be linear or
+logarithmic.  The values along the axis can either monotonically
+increase or decrease.  If you need custom tick labels, you can specify
+a Tcl procedure to format the label any way you wish.  You can
+control how ticks are drawn, by changing the major tick interval
+or the number of minor ticks.  You can define non-uniform tick intervals,
+such as for time-series plots.
+.PP
+.TP
+\fIpathName \fBaxis \fBcget \fIaxisName \fIoption\fR
+Returns the current value of the option given by \fIoption\fR for
+\fIaxisName\fR.  \fIOption\fR may be any option described below
+for the axis \fBconfigure\fR operation.
+.TP
+\fIpathName \fBaxis \fBconfigure \fIaxisName \fR?\fIaxisName\fR?... ?\fIoption value\fR?...
+Queries or modifies the configuration options of \fIaxisName\fR.
+Several axes can be changed.  If \fIoption\fR isn't specified, a list
+describing all the current options for \fIaxisName\fR is returned.  If
+\fIoption\fR is specified, but not \fIvalue\fR, then a list describing
+\fIoption\fR is returned.  If one or more \fIoption\fR and \fIvalue\fR
+pairs are specified, then for each pair, the axis option \fIoption\fR
+is set to \fIvalue\fR.  The following options are valid for axes.
+.RS
+.TP
+\fB\-autorange \fIrange\fR 
+Sets the range of values for the axis to \fIrange\fR.  The axis limits
+are automatically reset to display the most recent data points in this range.  
+If \fIrange\fR is 0.0, the range is
+determined from the limits of the data.  If \fB\-min\fR or \fB-max\fR
+are specified, they override this option.  The default is \f(CW0.0\fR.
+.TP
+\fB\-color \fIcolor\fR
+Sets the color of the axis and tick labels.
+The default is \f(CWblack\fR.
+.TP
+\fB\-command \fIprefix\fR
+Specifies a Tcl command to be invoked when formatting the axis tick
+labels. \fIPrefix\fR is a string containing the name of a Tcl proc and
+any extra arguments for the procedure.  This command is invoked for each
+major tick on the axis.  Two additional arguments are passed to the
+procedure: the pathname of the widget and the current the numeric
+value of the tick.  The procedure returns the formatted tick label.  If
+\f(CW""\fR is returned, no label will appear next to the tick.  You can
+get the standard tick labels again by setting \fIprefix\fR to
+\f(CW""\fR.  The default is \f(CW""\fR.
+.sp 1
+Please note that this procedure is invoked while the bar chart is redrawn.
+You may query the widget's configuration options.  But do not reset
+options, because this can have unexpected results.
+.TP
+\fB\-descending \fIboolean\fR 
+Indicates whether the values along the axis are monotonically increasing or
+decreasing.  If \fIboolean\fR is true, the axis values will be
+decreasing.  The default is \f(CW0\fR.
+.TP
+\fB\-hide \fIboolean\fR
+Indicates whether the axis is displayed. 
+.TP
+\fB\-justify \fIjustify\fR
+Specifies how the axis title should be justified.  This matters only
+when the axis title contains more than one line of text. \fIJustify\fR
+must be \f(CWleft\fR, \f(CWright\fR, or \f(CWcenter\fR.  The default is
+\f(CWcenter\fR.
+.TP
+\fB\-limits \fIformatStr\fR
+Specifies a printf-like description to format the minimum and maximum
+limits of the axis.  The limits are displayed at the top/bottom or
+left/right sides of the plotting area.  \fIFormatStr\fR is a list of
+one or two format descriptions.  If one description is supplied, both
+the minimum and maximum limits are formatted in the same way.  If two,
+the first designates the format for the minimum limit, the second for
+the maximum.  If \f(CW""\fR is given as either description, then 
+the that limit will not be displayed.  The default is \f(CW""\fR.
+.TP
+\fB\-linewidth \fIpixels\fR
+Sets the width of the axis and tick lines.  The default is \f(CW1\fR
+pixel.
+.TP
+\fB\-logscale \fIboolean\fR
+Indicates whether the scale of the axis is logarithmic or linear.  If
+\fIboolean\fR is true, the axis is logarithmic.  The default scale is
+linear.
+.TP
+\fB\-loose \fIboolean\fR
+Indicates whether the limits of the axis should fit the data points tightly,
+at the outermost data points, or loosely, at the outer tick intervals.
+This is relevant only when the axis limit is automatically calculated.
+If \fIboolean\fR is true, the axis range is "loose".
+The default is \f(CW0\fR.
+.TP
+\fB\-majorticks \fImajorList\fR
+Specifies where to display major axis ticks.  You can use this option
+to display ticks at non-uniform intervals.  \fIMajorList\fR is a list
+of axis coordinates designating the location of major ticks.  No
+minor ticks are drawn.  If \fImajorList\fR is \f(CW""\fR, 
+major ticks will be automatically computed. The default is \f(CW""\fR.
+.TP
+\fB\-max \fIvalue\fR
+Sets the maximum limit of \fIaxisName\fR.  Any data point greater 
+than \fIvalue\fR is not displayed.  If \fIvalue\fR is \f(CW""\fR, 
+the maximum limit is calculated using the largest data value.
+The default is \f(CW""\fR.
+.TP
+\fB\-min \fIvalue\fR
+Sets the minimum limit of \fIaxisName\fR. Any data point less than 
+\fIvalue\fR is not displayed.  If \fIvalue\fR is \f(CW""\fR,
+the minimum limit is calculated using the smallest data value.
+The default is \f(CW""\fR.
+.TP
+\fB\-minorticks \fIminorList\fR
+Specifies where to display minor axis ticks.  You can use this option
+to display minor ticks at non-uniform intervals. \fIMinorList\fR is a
+list of real values, ranging from 0.0 to 1.0, designating the placement of
+a minor tick.  No minor ticks are drawn if the \fB\-majortick\fR
+option is also set.  If \fIminorList\fR is \f(CW""\fR, minor ticks will
+be automatically computed. The default is \f(CW""\fR.
+.TP
+\fB\-rotate \fItheta\fR
+Specifies the how many degrees to rotate the axis tick labels.
+\fITheta\fR is a real value representing the number of degrees
+to rotate the tick labels.  The default is \f(CW0.0\fR degrees.
+.TP
+\fB\-shiftby \fIvalue\fR
+Specifies how much to automatically shift the range of the axis.
+When the new data exceeds the current axis maximum, the maximum
+is increased in increments of \fIvalue\fR.  You can use this
+option to prevent the axis limits from being recomputed
+at each new time point. If \fIvalue\fR is 0.0, then no automatic
+shifting is down. The default is \f(CW0.0\fR.
+.TP
+\fB\-showticks \fIboolean\fR
+Indicates whether axis ticks should be drawn. If \fIboolean\fR is
+true, ticks are drawn.  If false, only the
+axis line is drawn. The default is \f(CW1\fR.
+.TP
+\fB\-stepsize \fIvalue\fR
+Specifies the interval between major axis ticks.  If \fIvalue\fR isn't
+a valid interval (must be less than the axis range), 
+the request is ignored and the step size is automatically calculated.
+.TP
+\fB\-subdivisions \fInumber\fR 
+Indicates how many minor axis ticks are
+to be drawn.  For example, if \fInumber\fR is two, only one minor
+tick is drawn.  If \fInumber\fR is one, no minor ticks are
+displayed.  The default is \f(CW2\fR.
+.TP
+\fB\-tickfont \fIfontName\fR 
+Specifies the font for axis tick labels. The default is
+\f(CW*-Courier-Bold-R-Normal-*-100-*\fR.
+.TP
+\fB\-ticklength \fIpixels\fR
+Sets the length of major and minor ticks (minor ticks are half the
+length of major ticks). If \fIpixels\fR is less than zero, the axis
+will be inverted with ticks drawn pointing towards the plot.  The
+default is \f(CW0.1i\fR.
+.TP
+\fB\-title \fItext\fR
+Sets the title of the axis. If \fItext\fR is 
+\f(CW""\fR, no axis title will be displayed.  
+.TP
+\fB\-titlecolor \fIcolor\fR
+Sets the color of the axis title. The default is \f(CWblack\fR.
+.TP
+\fB\-titlefont \fIfontName\fR 
+Specifies the font for axis title. The default is
+\f(CW*-Helvetica-Bold-R-Normal-*-14-140-*\fR.
+.PP
+Axis configuration options may be also be set by the \fBoption\fR
+command.  The resource class is \f(CWAxis\fR.  The resource names
+are the names of the axes (such as \f(CWx\fR or \f(CWx2\fR).
+.CS
+option add *Barchart.Axis.Color  blue
+option add *Barchart.x.LogScale  true
+option add *Barchart.x2.LogScale false
+.CE
+.RE
+.TP
+\fIpathName \fBaxis \fBcreate \fIaxisName \fR?\fIoption value\fR?...
+Creates a new axis by the name \fIaxisName\fR.  No axis by the same
+name can already exist. \fIOption\fR and \fIvalue\fR are described 
+in above in the axis \fBconfigure\fR operation.
+.TP
+\fIpathName \fBaxis \fBdelete \fR?\fIaxisName\fR?...
+Deletes the named axes. An axis is not really
+deleted until it is not longer in use, so it's safe to delete
+axes mapped to elements.
+.TP
+\fIpathName \fBaxis invtransform \fIaxisName value\fR
+Performs the inverse transformation, changing the screen-coordinate
+\fIvalue\fR to a graph-coordinate, mapping the value mapped to
+\fIaxisName\fR.  Returns the graph-coordinate.
+.TP
+\fIpathName \fBaxis limits \fIaxisName\fR
+Returns a list of the minimum and maximum limits for \fIaxisName\fR.  The order
+of the list is \f(CWmin max\fR.
+.TP
+\fIpathName \fBaxis names \fR?\fIpattern\fR?...
+Returns a list of axes matching zero or more patterns.  If no
+\fIpattern\fR argument is give, the names of all axes are returned.
+.TP
+\fIpathName \fBaxis transform \fIaxisName value\fR
+Transforms the coordinate \fIvalue\fR to a screen-coordinate by mapping
+the it to \fIaxisName\fR.  Returns the transformed screen-coordinate.
+.PP
+Only four axes can be displayed simultaneously.  By default, they are
+\f(CWx\fR, \f(CWy\fR, \f(CWx2\fR, and \f(CWy2\fR.  You can swap in a different
+axis with \fBuse\fR operation of the special axis components:
+\fBxaxis\fR, \fBx2axis\fR, \fByaxis\fR, and \fBy2axis\fR.
+.CS
+\&.g create axis temp
+\&.g create axis time
+\&...
+\&.g xaxis use temp
+\&.g yaxis use time
+.CE
+Only the axes specified for use are displayed on the screen.
+.PP
+The \fBxaxis\fR, \fBx2axis\fR, \fByaxis\fR, and \fBy2axis\fR
+components operate on an axis location rather than a specific axis
+like the more general \fBaxis\fR component does.  The \fBxaxis\fR
+component manages the X-axis located in the bottom margin (whatever
+axis that happens to be).  Likewise, \fByaxis\fR uses the Y-axis in
+the left margin, \fBx2axis\fR the top X-axis, and \fBy2axis\fR the
+right Y-axis.
+.PP
+They implicitly control the axis that is currently using to that
+location.  By default, \fBxaxis\fR uses the \f(CWx\fR axis, \fByaxis\fR
+uses \f(CWy\fR, \fBx2axis\fR uses \f(CWx2\fR, and \fBy2axis\fR uses
+\f(CWy2\fR.  These components can be more convenient to use than always
+determining what axes are current being displayed by the graph.
+.PP
+The following operations are available for axes. They mirror exactly
+the operations of the \fBaxis\fR component.  The \fIaxis\fR argument
+must be \fBxaxis\fR, \fBx2axis\fR, \fByaxis\fR, or \fBy2axis\fR.
+.TP
+\fIpathName \fIaxis \fBcget \fIoption\fR
+.TP
+\fIpathName \fIaxis \fBconfigure \fR?\fIoption value\fR?...
+.TP
+\fIpathName \fIaxis\fB invtransform \fIvalue\fR
+.TP
+\fIpathName \fIaxis \fBlimits\fR
+.TP
+\fIpathName \fIaxis\fB transform \fIvalue\fR
+.TP
+\fIpathName \fIaxis\fB use \fR?\fIaxisName\fR?  
+Designates the axis \fIaxisName\fR is to be displayed at this
+location.  \fIAxisName\fR can not be already in use at another location.  
+This command returns the name of the axis currently using this location.
+.SS "CROSSHAIRS COMPONENT"
+Cross hairs consist of two intersecting lines (one vertical and one horizontal)
+drawn completely across the plotting area.  They are used to position
+the mouse in relation to the coordinate axes.  Cross hairs differ from line
+markers in that they are implemented using XOR drawing primitives.
+This means that they can be quickly drawn and erased without redrawing
+the entire widget.
+.PP
+The following operations are available for cross hairs:
+.TP
+\fIpathName \fBcrosshairs cget \fIoption\fR
+Returns the current value of the cross hairs configuration option
+given by \fIoption\fR.  \fIOption\fR may be any option
+described below for the cross hairs \fBconfigure\fR operation.
+.TP
+\fIpathName \fBcrosshairs configure \fR?\fIoption value\fR?...  
+Queries or modifies the configuration options of the cross hairs.  If
+\fIoption\fR isn't specified, a list describing all the current
+options for the cross hairs is returned.  If \fIoption\fR is specified,
+but not \fIvalue\fR, then a list describing \fIoption\fR is returned.
+If one or more \fIoption\fR and \fIvalue\fR pairs are specified, then
+for each pair, the cross hairs option \fIoption\fR is set to
+\fIvalue\fR.
+The following options are available for cross hairs.
+.RS
+.TP
+\fB\-color \fIcolor\fR 
+Sets the color of the cross hairs.  The default is \f(CWblack\fR.
+.TP
+\fB\-dashes \fIdashList\fR
+Sets the dash style of the cross hairs. \fIDashList\fR is a list of up
+to 11 numbers that alternately represent the lengths of the dashes
+and gaps on the cross hair lines.  Each number must be between 1 and
+255.  If \fIdashList\fR is \f(CW""\fR, the cross hairs will be solid
+lines.
+.TP
+\fB\-hide \fIboolean\fR
+Indicates whether cross hairs are drawn. If \fIboolean\fR is true,
+cross hairs are not drawn.  The default is \f(CWyes\fR.
+.TP
+\fB\-linewidth \fIpixels\fR
+Set the width of the cross hair lines.  The default is \f(CW1\fR.
+.TP
+\fB\-position \fIpos\fR 
+Specifies the screen position where the cross hairs intersect.
+\fIPos\fR must be in the form "\fI@x,y\fR", where \fIx\fR and \fIy\fR
+are the window coordinates of the intersection.
+.PP
+Cross hairs configuration options may be also be set by the
+\fBoption\fR command.  The resource name and class are
+\f(CWcrosshairs\fR and \f(CWCrosshairs\fR respectively.
+.CS
+option add *Barchart.Crosshairs.LineWidth 2
+option add *Barchart.Crosshairs.Color     red
+.CE
+.RE
+.TP
+\fIpathName \fBcrosshairs off\fR
+Turns off the cross hairs. 
+.TP
+\fIpathName \fBcrosshairs on\fR
+Turns on the display of the cross hairs.
+.TP
+\fIpathName \fBcrosshairs toggle\fR 
+Toggles the current state of the cross hairs, alternately mapping and
+unmapping the cross hairs.
+.SH "ELEMENTS"
+A data element represents a set of data.  It contains x and y vectors
+which are the coordinates of the data points.  Elements are displayed
+as bars where the length of the bar is proportional to the ordinate of
+the data point.  Elements also control the appearance of the data,
+such as the color, stipple, relief, etc.
+.PP
+When new data elements are created, they are automatically added to a
+list of displayed elements.   The display list controls what elements
+are drawn and in what order.  
+.PP
+The following operations are available for elements.
+.TP
+\fIpathName \fBelement activate \fIelemName \fR?\fIindex\fR?...
+Specifies the data points of element \fIelemName\fR to be drawn
+using active foreground and background colors.  \fIElemName\fR is the
+name of the element and \fIindex\fR is a number representing the index
+of the data point. If no indices are present then all data points
+become active.
+.TP
+\fIpathName \fBelement bind \fItagName\fR ?\fIsequence\fR?  ?\fIcommand\fR? 
+Associates \fIcommand\fR with \fItagName\fR such that whenever the
+event sequence given by \fIsequence\fR occurs for an element with this
+tag, \fIcommand\fR will be invoked.  The syntax is similar to the 
+\fBbind\fR command except that it operates on graph elements, rather 
+than widgets. See the \fBbind\fR manual entry for
+complete details on \fIsequence\fR and the substitutions performed on 
+\fIcommand\fR before invoking it.  
+.sp
+If all arguments are specified then a new binding is created, replacing 
+any existing binding for the same \fIsequence\fR and \fItagName\fR.
+If the first character of \fIcommand\fR is \f(CW+\fR then \fIcommand\fR 
+augments an existing binding rather than replacing it. 
+If no \fIcommand\fR argument is provided then the command currently
+associated with \fItagName\fR and \fIsequence\fR (it's an error occurs 
+if there's no such binding) is returned.  If both \fIcommand\fR and 
+\fIsequence\fR are missing then a list of all the event sequences for 
+which bindings have been defined for \fItagName\fR. 
+.TP
+\fIpathName \fBelement cget \fIelemName \fIoption\fR
+Returns the current value of the element configuration option given by 
+\fIoption\fR.  \fIOption\fR may be any of the options described below
+for the element \fBconfigure\fR operation.
+.TP
+\fIpathName \fBelement closest \fIx y\fR ?\fIoption value\fR?... ?\fIelemName\fR?...
+Finds the data point representing the bar closest to the window
+coordinates \fIx\fR and \fIy\fR in the element \fIelemName\fR.
+\fIElemName\fR is the name of an element, which must be currently displayed.  
+If no elements are specified, then all displayed elements are searched.  It
+returns a key-value list containing the name of the closest element, 
+the index of its closest point, and the graph-coordinates of the
+point. If no data point within the threshold distance can be found,
+\f(CW""\fR is returned.  The following \fIoption\fR-\fIvalue\fR pairs
+are available.
+.RS
+.TP
+\fB\-halo \fIpixels\fR
+Specifies a threshold distance where selected data points are ignored.
+\fIPixels\fR is a valid screen distance, such as \f(CW2\fR or \f(CW1.2i\fR.
+If this option isn't specified, then it defaults to the value of the
+\fBbarchart\fR's \fB\-halo\fR option.
+.RE
+.TP
+\fIpathName \fBelement configure \fIelemName \fR?\fIelemName\fR... ?\fIoption value\fR?...
+Queries or modifies the configuration options for elements.  Several
+elements can be modified at the same time. If \fIoption\fR isn't
+specified, a list describing all the current options for
+\fIelemName\fR is returned.  If \fIoption\fR is specified, but not
+\fIvalue\fR, then a list describing the option \fIoption\fR is
+returned.  If one or more \fIoption\fR and \fIvalue\fR pairs are
+specified, then for each pair, the element option \fIoption\fR is set
+to \fIvalue\fR.  The following options are valid for elements.
+.RS
+.TP
+\fB\-activepen \fIpenName\fR
+Specifies pen to use to draw active element.  If \fIpenName\fR is
+\f(CW""\fR, no active elements will be drawn.  The default is 
+\f(CWactiveLine\fR.
+.TP
+\fB\-bindtags \fItagList\fR
+Specifies the binding tags for the element.  \fITagList\fR is a list
+of binding tag names.  The tags and their order will determine how
+events for elements.  Each tag in the list matching the current event
+sequence will have its Tcl command executed.  Implicitly the name of
+the element is always the first tag in the list.  The default value is
+\f(CWall\fR.
+.TP
+\fB\-background \fIcolor\fR
+Sets the the color of the border around each bar.  The default is
+\f(CWwhite\fR.
+.TP
+\fB\-barwidth \fIvalue\fR 
+Specifies the width the bars drawn for the element.  \fIValue\fR is
+the width in X-coordinates.  If this option isn't
+specified, the width of each bar is the value of the widget's
+\fB\-barwidth\fR option.
+.TP
+\fB\-baseline \fIvalue\fR 
+Specifies the baseline of the bar segments.  This affects how bars are 
+drawn since bars are drawn from their respective y-coordinate the 
+baseline. By default the baseline is \f(CW0.0\fR.  
+.TP
+\fB\-borderwidth \fIpixels\fR
+Sets the border width of the 3-D border drawn around the outside of
+each bar.  The \fB\-relief\fR option determines if such a border is
+drawn.  \fIPixels\fR must be a valid screen distance like \f(CW2\fR or
+\f(CW0.25i\fR. The default is \f(CW2\fR.
+.TP
+\fB\-data \fIcoordList\fR
+Specifies the X\-Y coordinates of the data.  \fICoordList\fR is a
+list of numeric expressions representing the X\-Y coordinate pairs
+of each data point.
+.TP
+\fB\-foreground \fIcolor\fR 
+Sets the color of the interior of the bars.  
+.TP
+\fB\-hide \fIboolean\fR
+Indicates whether the element is displayed.  The default is \f(CWno\fR.
+.TP
+\fB\-label \fItext\fR
+Sets the element's label in the legend.  If \fItext\fR
+is \f(CW""\fR, the element will have no entry in the legend.
+The default label is the element's name.
+.TP
+\fB\-mapx \fIxAxis\fR
+Selects the X\-axis to map the element's X\-coordinates onto.
+\fIXAxis\fR must be the name of an axis.  The default is \f(CWx\fR.
+.TP
+\fB\-mapy \fIyAxis\fR
+Selects the Y\-axis to map the element's Y\-coordinates onto.
+\fIYAxis\fR must be the name of an axis. The default is \f(CWy\fR.
+.TP
+\fB\-relief \fIstring\fR
+Specifies the 3-D effect desired for bars.  \fIRelief\fR indicates how
+the interior of the bar should appear relative to the surface of the
+chart; for example, \f(CWraised\fR means the bar should appear to
+protrude from the surface of the plotting area.  The default is
+\f(CWraised\fR.
+.TP
+\fB\-stipple \fIbitmap\fR
+Specifies a stipple pattern with which to draw the bars.  If
+\fIbitmap\fR is \f(CW""\fR, then the bar is drawn in a solid fashion.
+.TP
+\fB\-xdata \fIxVector\fR 
+Specifies the x-coordinate vector of the data.
+\fIXVector\fR is the name of a BLT vector or a
+list of numeric expressions.  
+.TP
+\fB\-ydata \fIyVector\fR 
+Specifies the y-coordinate vector of the data.
+\fIYVector\fR is the name of a BLT vector or a list of
+numeric expressions.  
+.PP
+Element configuration options may also be set by the 
+\fBoption\fR command.  The resource names  in the option database 
+are prefixed by \f(CWelem\fR.
+.CS
+option add *Barchart.Element.background blue
+.CE
+.RE
+.TP
+\fIpathName \fBelement create \fIelemName\fR ?\fIoption value\fR?...
+Creates a new element \fIelemName\fR.  Element
+names must be unique, so an element \fIelemName\fR may not already
+exist.  If additional arguments are present, they specify any of the
+element options valid for element \fBconfigure\fR operation.
+.TP
+\fIpathName \fBelement deactivate \fIpattern\fR...
+Deactivates all the elements matching \fIpattern\fR for the graph.  
+Elements whose names match any of the patterns given are redrawn 
+using their normal colors.  
+.TP
+\fIpathName \fBelement delete\fR ?\fIpattern\fR?...
+Deletes all the elements matching \fIpattern\fR for the graph.  
+Elements whose names match any of the patterns given are deleted. 
+The graph will be redrawn without the deleted elements.  
+.TP
+\fIpathName \fBelement exists \fIelemName\fR
+Returns \f(CW1\fR if an element \fIelemName\fR currently exists and
+\f(CW0\fR otherwise.
+.TP
+\fIpathName \fBelement names \fR?\fIpattern\fR?...  
+Returns the elements matching one or more pattern.  If no
+\fIpattern\fR is given, the names of all elements is returned.
+.TP
+\fIpathName \fBelement show\fR ?\fInameList\fR?  
+Queries or modifies the element display list.  The element display
+list designates the elements drawn and in what
+order. \fINameList\fR is a list of elements to be displayed in the
+order they are named.  If there is no \fInameList\fR argument,
+the current display list is returned.
+.TP
+\fIpathName \fBelement type\fR \fIelemName\fR
+Returns the type of \fIelemName\fR. 
+If the element is a bar element, the commands returns the string
+\f(CW"bar"\fR, otherwise it returns \f(CW"line"\fR.
+.CE
+.SS "GRID COMPONENT"
+Grid lines extend from the major and minor ticks of each axis
+horizontally or vertically across the plotting area.  The following
+operations are available for grid lines.
+.TP
+\fIpathName \fBgrid cget \fIoption\fR
+Returns the current value of the grid line configuration option given by 
+\fIoption\fR.  \fIOption\fR may be any option described below
+for the grid \fBconfigure\fR operation.
+.TP
+\fIpathName \fBgrid configure\fR ?\fIoption value\fR?...
+Queries or modifies the configuration options for grid lines.  If
+\fIoption\fR isn't specified, a list describing all the current
+grid options for \fIpathName\fR is returned.  If \fIoption\fR is specified,
+but not \fIvalue\fR, then a list describing \fIoption\fR is
+returned.  If one or more \fIoption\fR and \fIvalue\fR pairs are
+specified, then for each pair, the grid line option \fIoption\fR is set to
+\fIvalue\fR.  The following options are valid for grid lines.
+.RS
+.TP
+\fB\-color \fIcolor\fR 
+Sets the color of the grid lines.  The default is \f(CWblack\fR.
+.TP
+\fB\-dashes \fIdashList\fR
+Sets the dash style of the grid lines. \fIDashList\fR is a list of up
+to 11 numbers that alternately represent the lengths of the dashes
+and gaps on the grid lines.  Each number must be between 1 and 255.
+If \fIdashList\fR is \f(CW""\fR, the grid will be solid lines.
+.TP
+\fB\-hide \fIboolean\fR
+Indicates whether the grid should be drawn. If \fIboolean\fR
+is true, grid lines are not shown. The default is \f(CWyes\fR.
+.TP
+\fB\-linewidth \fIpixels\fR
+Sets the width of grid lines.  The default width is \f(CW1\fR.
+.TP
+\fB\-mapx \fIxAxis\fR
+Specifies the X\-axis to display grid lines.  \fIXAxis\fR
+must be the name of an axis or \f(CW""\fR for no grid lines.  
+The default is \f(CW""\fR.
+.TP
+\fB\-mapy \fIyAxis\fR
+Specifies the Y\-axis to display grid lines.  \fIYAxis\fR
+must be the name of an axis or \f(CW""\fR for no grid lines. 
+The default is \f(CWy\fR.
+.TP
+\fB\-minor \fIboolean\fR
+Indicates whether the grid lines should be drawn for minor ticks. 
+If \fIboolean\fR is true, the lines will appear at
+minor tick intervals.  The default is \f(CW1\fR.
+.PP
+Grid configuration options may also be set by the 
+\fBoption\fR command.  The resource name and class are \f(CWgrid\fR and 
+\f(CWGrid\fR respectively. 
+.CS
+option add *Barchart.grid.LineWidth 2
+option add *Barchart.Grid.Color     black
+.CE
+.RE
+.TP
+\fIpathName \fBgrid off\fR
+Turns off the display the grid lines.
+.TP
+\fIpathName \fBgrid on\fR
+Turns on the display the grid lines.
+.TP
+\fIpathName \fBgrid toggle\fR
+Toggles the display of the grid.  
+.SS "LEGEND COMPONENT"
+The legend displays a list of the data elements.  Each entry consists
+of the element's symbol and label.  The legend can appear in any
+margin (the default location is in the right margin).  It
+can also be positioned anywhere within the plotting area.
+.PP
+The following operations are valid for the legend.
+.TP
+\fIpathName \fBlegend activate \fIpattern\fR...
+Selects legend entries to be drawn using the active legend colors and relief.
+All entries whose element names match \fIpattern\fR  are selected.  To
+be selected, the element name must match only one \fIpattern\fR. 
+.TP
+\fIpathName \fBlegend bind \fItagName\fR ?\fIsequence\fR?  ?\fIcommand\fR? 
+Associates \fIcommand\fR with \fItagName\fR such that whenever the
+event sequence given by \fIsequence\fR occurs for a legend entry with this
+tag, \fIcommand\fR will be invoked.  Implicitly the element names
+in the entry are tags.  The syntax is similar to the 
+\fBbind\fR command except that it operates on legend entries, rather 
+than widgets. See the \fBbind\fR manual entry for
+complete details on \fIsequence\fR and the substitutions performed on 
+\fIcommand\fR before invoking it.  
+.sp
+If all arguments are specified then a new binding is created, replacing 
+any existing binding for the same \fIsequence\fR and \fItagName\fR.
+If the first character of \fIcommand\fR is \f(CW+\fR then \fIcommand\fR 
+augments an existing binding rather than replacing it. 
+If no \fIcommand\fR argument is provided then the command currently
+associated with \fItagName\fR and \fIsequence\fR (it's an error occurs 
+if there's no such binding) is returned.  If both \fIcommand\fR and 
+\fIsequence\fR are missing then a list of all the event sequences for 
+which bindings have been defined for \fItagName\fR. 
+.TP
+\fIpathName \fBlegend cget \fIoption\fR
+Returns the current value of a legend configuration option.
+\fIOption\fR may be any option described below in the
+legend \fBconfigure\fR operation.
+.TP
+\fIpathName \fBlegend configure \fR?\fIoption value\fR?...
+Queries or modifies the configuration options for the legend.  If
+\fIoption\fR isn't specified, a list describing the current
+legend options for \fIpathName\fR is returned.  If \fIoption\fR is
+specified, but not \fIvalue\fR, then a list describing \fIoption\fR is
+returned.  If one or more \fIoption\fR and \fIvalue\fR pairs are
+specified, then for each pair, the legend option \fIoption\fR is set
+to \fIvalue\fR.  The following options are valid for the legend.
+.RS
+.TP
+\fB\-activebackground \fIcolor\fR
+Sets the background color for active legend entries.  All legend
+entries marked active (see the legend \fBactivate\fR operation) are
+drawn using this background color.
+.TP
+\fB\-activeborderwidth \fIpixels\fR
+Sets the width of the 3-D border around the outside edge of the active legend
+entries.  The default is \f(CW2\fR.
+.TP
+\fB\-activeforeground \fIcolor\fR
+Sets the foreground color for active legend entries.  All legend
+entries marked as active (see the legend \fBactivate\fR operation) are
+drawn using this foreground color.
+.TP
+\fB\-activerelief \fIrelief\fR 
+Specifies the 3-D effect desired for active legend entries.
+\fIRelief\fR denotes how the interior of the entry should appear
+relative to the legend; for example, \f(CWraised\fR means the entry
+should appear to protrude from the legend, relative to the surface of
+the legend.  The default is \f(CWflat\fR.
+.TP
+\fB\-anchor \fIanchor\fR
+Tells how to position the legend relative to the positioning point for
+the legend.  This is dependent on the value of the \fB\-position\fR
+option.  The default is \f(CWcenter\fR.
+.RS
+.TP 1.25i
+\f(CWleft\fR or \f(CWright\fR
+The anchor describes how to position the legend vertically.  
+.TP
+\f(CWtop\fR or \f(CWbottom\fR
+The anchor describes how to position the legend horizontally.  
+.TP
+\f(CW@x,y\fR
+The anchor specifies how to position the legend relative to the
+positioning point. For example, if \fIanchor\fR is \f(CWcenter\fR then
+the legend is centered on the point; if \fIanchor\fR is \f(CWn\fR then
+the legend will be drawn such that the top center point of the
+rectangular region occupied by the legend will be at the positioning
+point.
+.TP
+\f(CWplotarea\fR
+The anchor specifies how to position the legend relative to the
+plotting area. For example, if \fIanchor\fR is \f(CWcenter\fR then the
+legend is centered in the plotting area; if \fIanchor\fR is \f(CWne\fR
+then the legend will be drawn such that occupies the upper right
+corner of the plotting area.
+.RE
+.TP
+\fB\-background \fIcolor\fR
+Sets the background color of the legend. If \fIcolor\fR is \f(CW""\fR,
+the legend background with be transparent.
+.TP
+\fB\-bindtags \fItagList\fR
+Specifies the binding tags for legend entries.  \fITagList\fR is a list
+of binding tag names.  The tags and their order will determine how
+events for legend entries.  Each tag in the list matching the current 
+event sequence will have its Tcl command executed. The default value 
+is \f(CWall\fR.
+.TP
+\fB\-borderwidth \fIpixels\fR
+Sets the width of the 3-D border around the outside edge of the legend (if
+such border is being drawn; the \fBrelief\fR option determines this).
+The default is \f(CW2\fR pixels.
+.TP
+\fB\-font \fIfontName\fR 
+\fIFontName\fR specifies a font to use when drawing the labels of each
+element into the legend.  The default is
+\f(CW*-Helvetica-Bold-R-Normal-*-12-120-*\fR.
+.TP
+\fB\-foreground \fIcolor\fR 
+Sets the foreground color of the text drawn for the element's label.
+The default is \f(CWblack\fR.
+.TP
+\fB\-hide \fIboolean\fR
+Indicates whether the legend should be displayed. If \fIboolean\fR is
+true, the legend will not be draw.  The default is \f(CWno\fR.
+.TP
+\fB\-ipadx \fIpad\fR 
+Sets the amount of internal padding to be added to the width of each
+legend entry.  \fIPad\fR can be a list of one or two screen distances.  If
+\fIpad\fR has two elements, the left side of the legend entry is
+padded by the first distance and the right side by the second.  If
+\fIpad\fR is just one distance, both the left and right sides are padded
+evenly.  The default is \f(CW2\fR.
+.TP
+\fB\-ipady \fIpad\fR
+Sets an amount of internal padding to be added to the height of each
+legend entry.  \fIPad\fR can be a list of one or two screen distances.  If
+\fIpad\fR has two elements, the top of the entry is padded by the
+first distance and the bottom by the second.  If \fIpad\fR is just
+one distance, both the top and bottom of the entry are padded evenly.
+The default is \f(CW2\fR.
+.TP
+\fB\-padx \fIpad\fR
+Sets the padding to the left and right exteriors of the legend.
+\fIPad\fR can be a list of one or two screen distances.  If \fIpad\fR
+has two elements, the left side of the legend is padded by the first
+distance and the right side by the second.  If \fIpad\fR has just one
+distance, both the left and right sides are padded evenly.  The
+default is \f(CW4\fR.
+.TP
+\fB\-pady \fIpad\fR
+Sets the padding above and below the legend.  \fIPad\fR can be a list
+of one or two screen distances.  If \fIpad\fR has two elements, the area above
+the legend is padded by the first distance and the area below by the
+second.  If \fIpad\fR is just one distance, both the top and
+bottom areas are padded evenly.  The default is \f(CW0\fR.
+.TP
+\fB\-position \fIpos\fR
+Specifies where the legend is drawn. The
+\fB\-anchor\fR option also affects where the legend is positioned.  If
+\fIpos\fR is \f(CWleft\fR, \f(CWleft\fR, \f(CWtop\fR, or \f(CWbottom\fR, the
+legend is drawn in the specified margin.  If \fIpos\fR is
+\f(CWplotarea\fR, then the legend is drawn inside the plotting area at a
+particular anchor.  If \fIpos\fR is in the form "\fI@x,y\fR", where
+\fIx\fR and \fIy\fR are the window coordinates, the legend is drawn in
+the plotting area at the specified coordinates.  The default is
+\f(CWright\fR.
+.TP
+\fB\-raised \fIboolean\fR
+Indicates whether the legend is above or below the data elements.  This
+matters only if the legend is in the plotting area.  If \fIboolean\fR
+is true, the legend will be drawn on top of any elements that may
+overlap it. The default is \f(CWno\fR.
+.TP
+\fB\-relief \fIrelief\fR
+Specifies the 3-D effect for the border around the legend.
+\fIRelief\fR specifies how the interior of the legend should appear
+relative to the bar chart; for example, \f(CWraised\fR means the legend
+should appear to protrude from the bar chart, relative to the surface of
+the bar chart.  The default is \f(CWsunken\fR.
+.PP
+Legend configuration options may also be set by the \fBoption\fR
+command.  The resource name and class are \f(CWlegend\fR and
+\f(CWLegend\fR respectively.
+.CS
+option add *Barchart.legend.Foreground blue
+option add *Barchart.Legend.Relief     raised
+.CE
+.RE
+.TP
+\fIpathName \fBlegend deactivate \fIpattern\fR...
+Selects legend entries to be drawn using the normal legend colors and
+relief.  All entries whose element names match \fIpattern\fR are
+selected.  To be selected, the element name must match only one
+\fIpattern\fR.
+.TP
+\fIpathName \fBlegend get \fIpos\fR
+Returns the name of the element whose entry is at the screen position
+\fIpos\fR in the legend.  \fIPos\fR must be in the form "\fI@x,y\fR",
+where \fIx\fR and \fIy\fR are window coordinates.  If the given
+coordinates do not lie over a legend entry, \f(CW""\fR is returned.
+.SS "PEN COMPONENTS"
+Pens define attributes for elements.
+Pens mirror the configuration options of data elements that pertain to
+how symbols and lines are drawn.  Data elements use pens to determine
+how they are drawn.  A data element may use several pens at once.  In
+this case, the pen used for a particular data point is determined from
+each element's weight vector (see the element's \fB\-weight\fR and
+\fB\-style\fR options).
+.PP
+One pen, called \f(CWactiveBar\fR, is automatically created.
+It's used as the default active pen for elements. So you can change
+the active attributes for all elements by simply reconfiguring this
+pen.
+.CS
+\&.g pen configure "activeBar" -fg green -bg green4
+.CE
+You can create and use several pens. To create a pen, invoke
+the pen component and its create operation.
+.CS
+\&.g pen create myPen
+.CE
+You map pens to a data element using either the element's 
+\fB\-pen\fR or \fB\-activepen\fR options.
+.CS
+\&.g element create "e1" -xdata $x -ydata $tempData \\
+    -pen myPen
+.CE
+An element can use several pens at once. This is done by specifying
+the name of the pen in the element's style list (see the
+\fB\-styles\fR option).
+.CS
+\&.g element configure "e1" -styles { myPen 2.0 3.0 }
+.CE
+This says that any data point with a weight between 2.0 and 3.0
+is to be drawn using the pen \f(CWmyPen\fR.  All other points
+are drawn with the element's default attributes.
+.PP
+The following operations are available for pen components.
+.PP
+.TP
+\fIpathName \fBpen \fBcget \fIpenName \fIoption\fR
+Returns the current value of the option given by \fIoption\fR for
+\fIpenName\fR.  \fIOption\fR may be any option described below
+for the pen \fBconfigure\fR operation.
+.TP
+\fIpathName \fBpen \fBconfigure \fIpenName \fR?\fIpenName\fR... ?\fIoption value\fR?...
+Queries or modifies the configuration options of
+\fIpenName\fR. Several pens can be modified at once.  If \fIoption\fR
+isn't specified, a list describing the current options for
+\fIpenName\fR is returned.  If \fIoption\fR is specified, but not
+\fIvalue\fR, then a list describing \fIoption\fR is returned.  If one
+or more \fIoption\fR and \fIvalue\fR pairs are specified, then for
+each pair, the pen option \fIoption\fR is set to \fIvalue\fR.  The
+following options are valid for pens.
+.RS
+.TP
+\fB\-background \fIcolor\fR
+Sets the the color of the border around each bar.  The default is
+\f(CWwhite\fR.
+.TP
+\fB\-borderwidth \fIpixels\fR
+Sets the border width of the 3-D border drawn around the outside of
+each bar.  The \fB\-relief\fR option determines if such a border is
+drawn.  \fIPixels\fR must be a valid screen distance like \f(CW2\fR or
+\f(CW0.25i\fR. The default is \f(CW2\fR.
+.TP
+\fB\-foreground \fIcolor\fR 
+Sets the color of the interior of the bars.  
+.TP
+\fB\-relief \fIstring\fR
+Specifies the 3-D effect desired for bars.  \fIRelief\fR indicates how
+the interior of the bar should appear relative to the surface of the
+chart; for example, \f(CWraised\fR means the bar should appear to
+protrude from the bar chart, relative to the surface of the plotting
+area.  The default is \f(CWraised\fR.
+.TP
+\fB\-stipple \fIbitmap\fR
+Specifies a stipple pattern with which to draw the bars.  If
+\fIbitmap\fR is \f(CW""\fR, then the bar is drawn in a solid fashion.
+.TP
+\fB\-type \fIelemType\fR 
+Specifies the type of element the pen is to be used with.
+This option should only be employed when creating the pen.  This
+is for those that wish to mix different types of elements (bars and
+lines) on the same graph.  The default type is "bar".
+.PP
+Pen configuration options may be also be set by the \fBoption\fR
+command.  The resource class is \f(CWPen\fR.  The resource names
+are the names of the pens.
+.CS
+option add *Barchart.Pen.Foreground	   blue
+option add *Barchart.activeBar.foreground  green
+.CE
+.RE
+.TP
+\fIpathName \fBpen \fBcreate \fIpenName \fR?\fIoption value\fR?...
+Creates a new pen by the name \fIpenName\fR.  No pen by the same
+name can already exist. \fIOption\fR and \fIvalue\fR are described 
+in above in the pen \fBconfigure\fR operation.
+.TP
+\fIpathName \fBpen \fBdelete \fR?\fIpenName\fR?...
+Deletes the named pens. A pen is not really
+deleted until it is not longer in use, so it's safe to delete
+pens mapped to elements.
+.TP
+\fIpathName \fBpen names \fR?\fIpattern\fR?...
+Returns a list of pens matching zero or more patterns.  If no
+\fIpattern\fR argument is give, the names of all pens are returned.
+.SS "POSTSCRIPT COMPONENT"
+The barchart can generate encapsulated PostScript output.  There
+are several configuration options you can specify to control how the
+plot will be generated.  You can change the page dimensions and
+borders.  The plot itself can be scaled, centered, or rotated to
+landscape.  The PostScript output can be written directly to a file or
+returned through the interpreter.
+.PP
+The following postscript operations are available.
+.TP
+\fIpathName \fBpostscript cget \fIoption\fR 
+Returns the current value of the postscript option given by
+\fIoption\fR.  \fIOption\fR may be any option described
+below for the postscript \fBconfigure\fR operation.
+.TP
+\fIpathName \fBpostscript configure \fR?\fIoption value\fR?...
+Queries or modifies the configuration options for PostScript
+generation.  If \fIoption\fR isn't specified, a list describing 
+the current postscript options for \fIpathName\fR is returned.  If
+\fIoption\fR is specified, but not \fIvalue\fR, then a list describing
+\fIoption\fR is returned.  If one or more \fIoption\fR and \fIvalue\fR
+pairs are specified, then for each pair, the postscript option
+\fIoption\fR is set to \fIvalue\fR.  The following postscript options
+are available.
+.RS
+.TP
+\fB\-center \fIboolean\fR
+Indicates whether the plot should be centered on the PostScript page.  If
+\fIboolean\fR is false, the plot will be placed in the upper left
+corner of the page.  The default is \f(CW1\fR.
+.TP
+\fB\-colormap \fIvarName\fR
+\fIVarName\fR must be the name of a global array variable that
+specifies a color mapping from the X color name to PostScript.  Each
+element of \fIvarName\fR must consist of PostScript code to set a
+particular color value (e.g. ``\f(CW1.0 1.0 0.0 setrgbcolor\fR'').  When
+generating color information in PostScript, the array variable \fIvarName\fR
+is checked if an element of the name as the color exists. If so, it uses 
+its value as the PostScript
+command to set the color.  If this option hasn't been specified, or if
+there isn't an entry in \fIvarName\fR for a given color, then it uses
+the red, green, and blue intensities from the X color.
+.TP
+\fB\-colormode \fImode\fR
+Specifies how to output color information.  \fIMode\fR must be either
+\f(CWcolor\fR (for full color output), \f(CWgray\fR (convert all colors to
+their gray-scale equivalents) or \f(CWmono\fR (convert foreground colors
+to black and background colors to white).  The default mode is
+\f(CWcolor\fR. 
+.TP
+\fB\-fontmap \fIvarName\fR
+\fIVarName\fR must be the name of a global array variable that
+specifies a font mapping from the X font name to PostScript.  Each
+element of \fIvarName\fR must consist of a Tcl list with one or two
+elements; the name and point size of a PostScript font.
+When outputting PostScript commands for a particular font, the array
+variable \fIvarName\fR is checked to see if an element by the 
+specified font exists.  If there is such an element, then the font
+information contained in that element is used in the PostScript
+output.  (If the point size is omitted from the list, the point size
+of the X font is used).  Otherwise the X font is examined in an
+attempt to guess what PostScript font to use.  This works only for
+fonts whose foundry property is \fIAdobe\fR (such as Times, Helvetica,
+Courier, etc.).  If all of this fails then the font defaults to
+\f(CWHelvetica-Bold\fR.
+.TP
+\fB\-decorations \fIboolean\fR
+Indicates whether PostScript commands to generate color backgrounds and 3-D
+borders will be output.  If \fIboolean\fR is false, the graph will
+background will be white and no 3-D borders will be generated. The
+default is \f(CW1\fR.
+.TP
+\fB\-height \fIpixels\fR
+Sets the height of the plot.  This lets you print the bar chart with a
+height different from the one drawn on the screen.  If
+\fIpixels\fR is 0, the height is the same as the widget's height.
+The default is \f(CW0\fR.
+.TP
+\fB\-landscape \fIboolean\fR
+If \fIboolean\fR is true, this specifies the printed area is to be
+rotated 90 degrees.  In non-rotated output the X\-axis of the printed
+area runs along the short dimension of the page (``portrait''
+orientation); in rotated output the X\-axis runs along the long
+dimension of the page (``landscape'' orientation).  Defaults to
+\f(CW0\fR.
+.TP
+\fB\-maxpect \fIboolean\fR
+Indicates to scale the plot so that it fills the PostScript page.
+The aspect ratio of the barchart is still retained.  The default is
+\f(CW0\fR.
+.TP
+\fB\-padx \fIpad\fR
+Sets the horizontal padding for the left and right page borders.  The
+borders are exterior to the plot.  \fIPad\fR can be a list of one or
+two screen distances.  If \fIpad\fR has two elements, the left border is padded
+by the first distance and the right border by the second.  If
+\fIpad\fR has just one distance, both the left and right borders are
+padded evenly.  The default is \f(CW1i\fR.
+.TP
+\fB\-pady \fIpad\fR 
+Sets the vertical padding for the top and bottom page borders. The
+borders are exterior to the plot.  \fIPad\fR can be a list of one or
+two screen distances.  If \fIpad\fR has two elements, the top border is padded
+by the first distance and the bottom border by the second.  If
+\fIpad\fR has just one distance, both the top and bottom borders are
+padded evenly.  The default is \f(CW1i\fR.
+.TP
+\fB\-paperheight \fIpixels\fR
+Sets the height of the postscript page.  This can be used to select
+between different page sizes (letter, A4, etc).  The default height is
+\f(CW11.0i\fR.
+.TP
+\fB\-paperwidth \fIpixels\fR
+Sets the width of the postscript page.  This can be used to select
+between different page sizes (letter, A4, etc).  The default width is
+\f(CW8.5i\fR.
+.TP
+\fB\-width \fIpixels\fR
+Sets the width of the plot.  This lets you generate a plot
+of a width different from that of the widget.  If \fIpixels\fR
+is 0, the width is the same as the widget's width.  The default is
+\f(CW0\fR.
+.PP
+Postscript configuration options may be also be set by the
+\fBoption\fR command.  The resource name and class are
+\f(CWpostscript\fR and \f(CWPostscript\fR respectively.
+.CS
+option add *Barchart.postscript.Decorations false
+option add *Barchart.Postscript.Landscape   true
+.CE
+.RE
+.TP
+\fIpathName \fBpostscript output \fR?\fIfileName\fR? ?\fIoption value\fR?...
+Outputs a file of encapsulated PostScript.  If a
+\fIfileName\fR argument isn't present, the command returns the
+PostScript. If any \fIoption-value\fR pairs are present, they set
+configuration options controlling how the PostScript is generated.
+\fIOption\fR and \fIvalue\fR can be anything accepted by the
+postscript \fBconfigure\fR operation above.
+.SS "MARKER COMPONENTS"
+Markers are simple drawing procedures used to annotate or highlight
+areas of the graph.  Markers have various types: text strings,
+bitmaps, images, connected lines, windows, or polygons.  They can be
+associated with a particular element, so that when the element is
+hidden or un-hidden, so is the marker.  By default, markers are the
+last items drawn, so that data elements will appear in
+behind them.  You can change this by configuring the \fB\-under\fR
+option.
+.PP
+Markers, in contrast to elements, don't affect the scaling of the
+coordinate axes.  They can also have \fIelastic\fR coordinates
+(specified by \f(CW-Inf\fR and \f(CWInf\fR respectively) that translate
+into the minimum or maximum limit of the axis.  For example, you can
+place a marker so it always remains in the lower left corner of the
+plotting area, by using the coordinates \f(CW-Inf\fR,\f(CW-Inf\fR.
+.PP
+The following operations are available for markers.
+.TP
+\fIpathName \fBmarker after \fImarkerId\fR ?\fIafterId\fR?
+Changes the order of the markers, drawing the first
+marker after the second.  If no second \fIafterId\fR argument is
+specified, the marker is placed at the end of the display list.  This
+command can be used to control how markers are displayed since markers
+are drawn in the order of this display list.
+.TP
+\fIpathName \fBmarker before \fImarkerId\fR ?\fIbeforeId\fR?
+Changes the order of the markers, drawing the first
+marker before the second.  If no second \fIbeforeId\fR argument is
+specified, the marker is placed at the beginning of the display list.
+This command can be used to control how markers are displayed since
+markers are drawn in the order of this display list.
+.TP
+\fIpathName \fBmarker bind \fItagName\fR ?\fIsequence\fR?  ?\fIcommand\fR? 
+Associates \fIcommand\fR with \fItagName\fR such that whenever the
+event sequence given by \fIsequence\fR occurs for a marker with this
+tag, \fIcommand\fR will be invoked.  The syntax is similar to the 
+\fBbind\fR command except that it operates on graph markers, rather 
+than widgets. See the \fBbind\fR manual entry for
+complete details on \fIsequence\fR and the substitutions performed on 
+\fIcommand\fR before invoking it.  
+.sp
+If all arguments are specified then a new binding is created, replacing 
+any existing binding for the same \fIsequence\fR and \fItagName\fR.
+If the first character of \fIcommand\fR is \f(CW+\fR then \fIcommand\fR 
+augments an existing binding rather than replacing it. 
+If no \fIcommand\fR argument is provided then the command currently
+associated with \fItagName\fR and \fIsequence\fR (it's an error occurs 
+if there's no such binding) is returned.  If both \fIcommand\fR and 
+\fIsequence\fR are missing then a list of all the event sequences for 
+which bindings have been defined for \fItagName\fR. 
+.TP
+\fIpathName \fBmarker cget \fIoption\fR
+Returns the current value of the marker configuration option given by
+\fIoption\fR.  \fIOption\fR may be any option described
+below in the \fBconfigure\fR operation.
+.TP
+\fIpathName \fBmarker configure \fImarkerId\fR ?\fIoption value\fR?...
+Queries or modifies the configuration options for markers.  If
+\fIoption\fR isn't specified, a list describing the current
+options for \fImarkerId\fR is returned.  If \fIoption\fR is specified,
+but not \fIvalue\fR, then a list describing \fIoption\fR is returned.
+If one or more \fIoption\fR and \fIvalue\fR pairs are specified, then
+for each pair, the marker option \fIoption\fR is set to \fIvalue\fR.
+.sp
+The following options are valid for all markers.
+Each type of marker also has its own type-specific options.  
+They are described in the sections below.
+.RS
+.TP
+\fB\-bindtags \fItagList\fR
+Specifies the binding tags for the marker.  \fITagList\fR is a list
+of binding tag names.  The tags and their order will determine how
+events for markers are handled.  Each tag in the list matching the 
+current event sequence will have its Tcl command executed.  Implicitly 
+the name of the marker is always the first tag in the list.
+The default value is \f(CWall\fR.
+.TP
+\fB\-coords \fIcoordList\fR
+Specifies the coordinates of the marker.  \fICoordList\fR is 
+a list of graph-coordinates.  The number of coordinates required
+is dependent on the type of marker.  Text, image, and window markers
+need only two coordinates (an X\-Y coordinate).   Bitmap markers
+can take either two or four coordinates (if four, they represent the
+corners of the bitmap). Line markers
+need at least four coordinates, polygons at least six.
+If \fIcoordList\fR is \f(CW""\fR, the marker will not be displayed.
+The default is \f(CW""\fR.
+.TP
+\fB\-element \fIelemName\fR
+Links the marker with the element \fIelemName\fR.  The marker is
+drawn only if the element is also currently displayed (see the
+element's \fBshow\fR operation).  If \fIelemName\fR is \f(CW""\fR, the
+marker is always drawn.  The default is \f(CW""\fR.
+.TP
+\fB\-hide \fIboolean\fR 
+Indicates whether the marker is drawn. If \fIboolean\fR is true,
+the marker is not drawn.  The default is \f(CWno\fR.
+.TP
+\fB\-mapx \fIxAxis\fR 
+Specifies the X\-axis to map the marker's X\-coordinates onto.
+\fIXAxis\fR must the name of an axis.  The default is \f(CWx\fR.
+.TP
+\fB\-mapy \fIyAxis\fR
+Specifies the Y\-axis to map the marker's Y\-coordinates onto.
+\fIYAxis\fR must the name of an axis.  The default is \f(CWy\fR.
+.TP
+\fB\-name \fImarkerId\fR
+Changes the identifier for the marker.  The identifier \fImarkerId\fR 
+can not already be used by another marker.  If this option
+isn't specified, the marker's name is uniquely generated.
+.TP
+\fB\-under \fIboolean\fR
+Indicates whether the marker is drawn below/above data
+elements.  If \fIboolean\fR is true, the marker is be drawn
+underneath the data elements.  Otherwise, the marker is
+drawn on top of the element.  The default is \f(CW0\fR.
+.TP
+\fB\-xoffset \fIpixels\fR
+Specifies a screen distance to offset the marker horizontally. 
+\fIPixels\fR is a valid screen distance, such as \f(CW2\fR or \f(CW1.2i\fR.
+The default is \f(CW0\fR.
+.TP
+\fB\-yoffset \fIpixels\fR
+Specifies a screen distance to offset the markers vertically.
+\fIPixels\fR is a valid screen distance, such as \f(CW2\fR or \f(CW1.2i\fR.
+The default is \f(CW0\fR.
+.PP
+Marker configuration options may also be set by the \fBoption\fR command.
+The resource class is either \f(CWBitmapMarker\fR,  \f(CWImageMarker\fR, 
+\f(CWLineMarker\fR, \f(CWPolygonMarker\fR, \f(CWTextMarker\fR, or \f(CWWindowMarker\fR,
+depending on the type of marker.  The resource name is the name of the
+marker.
+.CS
+option add *Barchart.TextMarker.Foreground white
+option add *Barchart.BitmapMarker.Foreground white
+option add *Barchart.m1.Background     blue
+.CE
+.RE
+.TP
+\fIpathName \fBmarker create \fItype\fR ?\fIoption value\fR?...
+Creates a marker of the selected type. \fIType\fR may be either
+\f(CWtext\fR, \f(CWline\fR, \f(CWbitmap\fR, \f(CWimage\fR, \f(CWpolygon\fR, or
+\f(CWwindow\fR.  This command returns the marker identifier, 
+used as the \fImarkerId\fR argument in the other marker-related
+commands.  If the \fB\-name\fR option is used, this overrides the
+normal marker identifier.  If the name provided is already used for
+another marker, the new marker will replace the old.
+.TP
+\fIpathName \fBmarker delete\fR ?\fIname\fR?...
+Removes one of more markers.  The graph will automatically be redrawn
+without the marker.\fR.  
+.TP
+\fIpathName \fBmarker exists \fImarkerId\fR 
+Returns \f(CW1\fR if the marker \fImarkerId\fR exists and \f(CW0\fR
+otherwise.
+.TP
+\fIpathName \fBmarker names\fR ?\fIpattern\fR?  
+Returns the names of all the markers that currently exist.  If
+\fIpattern\fR is supplied, only those markers whose names match it
+will be returned.
+.TP
+\fIpathName \fBmarker type \fImarkerId\fR 
+Returns the type of the marker given by \fImarkerId\fR, such as
+\f(CWline\fR or \f(CWtext\fR.  If \fImarkerId\fR is not a valid a marker
+identifier, \f(CW""\fR is returned.
+.SS "BITMAP MARKERS"
+A bitmap marker displays a bitmap.  The size of the
+bitmap is controlled by the number of coordinates specified.  If two
+coordinates, they specify the position of the top-left corner of the
+bitmap.  The bitmap retains its normal width and height.  If four
+coordinates, the first and second pairs of coordinates represent the
+corners of the bitmap.  The bitmap will be stretched or reduced as
+necessary to fit into the bounding rectangle.
+.PP
+Bitmap markers are created with the marker's \fBcreate\fR operation in
+the form:
+.DS
+\fIpathName \fBmarker create bitmap \fR?\fIoption value\fR?...
+.DE
+There may be many \fIoption\fR-\fIvalue\fR pairs, each 
+sets a configuration options for the marker.  These
+same \fIoption\fR\-\fIvalue\fR pairs may be used with the marker's
+\fBconfigure\fR operation.
+.PP
+The following options are specific to bitmap markers:
+.TP
+\fB\-background \fIcolor\fR
+Same as the \fB\-fill\fR option.
+.TP
+\fB\-bitmap \fIbitmap\fR
+Specifies the bitmap to be displayed.  If \fIbitmap\fR is \f(CW""\fR,
+the marker will not be displayed.  The default is \f(CW""\fR.
+.TP
+\fB\-fill \fIcolor\fR
+Sets the background color of the bitmap.  If \fIcolor\fR is the empty
+string, no background will be transparent.  The default background color is
+\f(CW""\fR.
+.TP
+\fB\-foreground \fIcolor\fR 
+Same as the \fB\-outline\fR option.
+.TP
+\fB\-mask \fImask\fR
+Specifies a mask for the bitmap to be displayed. This mask is a bitmap
+itself, denoting the pixels that are transparent.  If \fImask\fR is
+\f(CW""\fR, all pixels of the bitmap will be drawn.  The default is
+\f(CW""\fR.
+.TP
+\fB\-outline \fIcolor\fR
+Sets the foreground color of the bitmap. The default value is \f(CWblack\fR.
+.TP
+\fB\-rotate \fItheta\fR
+Sets the rotation of the bitmap.  \fITheta\fR is a real number
+representing the angle of rotation in degrees.  The marker is first
+rotated and then placed according to its anchor position.  The default
+rotation is \f(CW0.0\fR.
+.SS "IMAGE MARKERS"
+A image marker displays an image.  Image markers are
+created with the marker's \fBcreate\fR operation in the form:
+.DS
+\fIpathName \fBmarker create image \fR?\fIoption value\fR?...
+.DE
+There may be many \fIoption\fR-\fIvalue\fR
+pairs, each sets a configuration option
+for the marker.  These same \fIoption\fR\-\fIvalue\fR pairs may be
+used with the marker's \fBconfigure\fR operation.
+.PP
+The following options are specific to image markers:
+.TP
+\fB\-anchor \fIanchor\fR
+\fIAnchor\fR tells how to position the image relative to the
+positioning point for the image. For example, if \fIanchor\fR
+is \f(CWcenter\fR then the image is centered on the point;  if
+\fIanchor\fR is \f(CWn\fR then the image will be drawn such that
+the top center point of the rectangular region occupied by the
+image will be at the positioning point.
+This option defaults to \f(CWcenter\fR.
+.TP
+\fB\-image \fIimage\fR
+Specifies the image to be drawn.
+If \fIimage\fR is \f(CW""\fR, the marker will not be
+drawn.  The default is \f(CW""\fR.
+.SS "LINE MARKERS"
+A line marker displays one or more connected line segments.
+Line markers are created with marker's \fBcreate\fR operation in the form:
+.DS
+\fIpathName \fBmarker create line \fR?\fIoption value\fR?...
+.DE
+There may be many \fIoption\fR-\fIvalue\fR
+pairs, each sets a configuration option
+for the marker.  These same \fIoption\fR-\fIvalue\fR pairs may be
+used with the marker's \fBconfigure\fR operation.
+.PP
+The following options are specific to line markers:
+.TP
+\fB\-dashes \fIdashList\fR
+Sets the dash style of the line. \fIDashList\fR is a list of up to 11
+numbers that alternately represent the lengths of the dashes and gaps
+on the line.  Each number must be between 1 and 255.  If
+\fIdashList\fR is \f(CW""\fR, the marker line will be solid.
+.TP
+\fB\-fill \fIcolor\fR
+Sets the background color of the line.  This color is used with
+striped lines (see the \fB\-fdashes\R option). If \fIcolor\fR is
+the empty string, no background color is drawn (the line will be
+dashed, not striped).  The default background color is \f(CW""\fR.
+.TP
+\fB\-linewidth \fIpixels\fR
+Sets the width of the lines.
+The default width is \f(CW0\fR.
+.TP
+\fB\-outline \fIcolor\fR
+Sets the foreground color of the line. The default value is \f(CWblack\fR.
+.TP
+\fB\-stipple \fIbitmap\fR
+Specifies a stipple pattern used to draw the line, rather than
+a solid line.
+\fIBitmap\fR specifies a bitmap to use as the stipple
+pattern.  If \fIbitmap\fR is \f(CW""\fR, then the
+line is drawn in a solid fashion. The default is \f(CW""\fR.
+.SS "POLYGON MARKERS"
+A polygon marker displays a closed region described as two or more
+connected line segments.  It is assumed the first and
+last points are connected.  Polygon markers are created using the
+marker \fBcreate\fR operation in the form:
+.DS
+\fIpathName \fBmarker create polygon \fR?\fIoption value\fR?...
+.DE
+There may be many \fIoption\fR-\fIvalue\fR
+pairs, each sets a configuration option
+for the marker.  These same \fIoption\fR\-\fIvalue\fR pairs may be
+used with the \fBmarker configure\fR command to change the marker's
+configuration.
+The following options are supported for polygon markers:
+.TP
+\fB\-dashes \fIdashList\fR
+Sets the dash style of the outline of the polygon. \fIDashList\fR is a
+list of up to 11 numbers that alternately represent the lengths of
+the dashes and gaps on the outline.  Each number must be between 1 and
+255. If \fIdashList\fR is \f(CW""\fR, the outline will be a solid line.
+.TP
+\fB\-fill \fIcolor\fR
+Sets the fill color of the polygon.  If \fIcolor\fR is \f(CW""\fR, then
+the interior of the polygon is transparent.
+The default is \f(CWwhite\fR.
+.TP
+\fB\-linewidth \fIpixels\fR
+Sets the width of the outline of the polygon. If \fIpixels\fR is zero, 
+no outline is drawn. The default is \f(CW0\fR.
+.TP
+\fB\-outline \fIcolor\fR
+Sets the color of the outline of the polygon.  If the polygon is
+stippled (see the \fB\-stipple\fR option), then this represents the
+foreground color of the stipple.  The default is \f(CWblack\fR.
+.TP
+\fB\-stipple \fIbitmap\fR
+Specifies that the polygon should be drawn with a stippled pattern
+rather than a solid color. \fIBitmap\fR specifies a bitmap to use as
+the stipple pattern.  If \fIbitmap\fR is \f(CW""\fR, then the polygon is
+filled with a solid color (if the \fB\-fill\fR option is set).  The
+default is \f(CW""\fR.
+.SS "TEXT MARKERS"
+A text marker displays a string of characters on one or more lines of
+text.  Embedded newlines cause line breaks.  They may be used to
+annotate regions of the graph.  Text markers are created with the
+\fBcreate\fR operation in the form:
+.DS
+\fIpathName \fBmarker create text \fR?\fIoption value\fR?...
+.DE
+There may be many \fIoption\fR-\fIvalue\fR pairs, 
+each sets a configuration option for the text marker.  
+These same \fIoption\fR\-\fIvalue\fR pairs may be used with the 
+marker's \fBconfigure\fR operation.  
+.PP
+The following options are specific to text markers:
+.TP
+\fB\-anchor \fIanchor\fR
+\fIAnchor\fR tells how to position the text relative to the
+positioning point for the text. For example, if \fIanchor\fR is
+\f(CWcenter\fR then the text is centered on the point; if
+\fIanchor\fR is \f(CWn\fR then the text will be drawn such that the
+top center point of the rectangular region occupied by the text will
+be at the positioning point.  This default is \f(CWcenter\fR.
+.TP
+\fB\-background \fIcolor\fR
+Same as the \fB\-fill\fR option.
+.TP
+\fB\-font \fIfontName\fR
+Specifies the font of the text.  The default is
+\f(CW*-Helvetica-Bold-R-Normal-*-120-*\fR.
+.TP
+\fB\-fill \fIcolor\fR
+Sets the background color of the text.  If \fIcolor\fR is the empty
+string, no background will be transparent.  The default background color is
+\f(CW""\fR.
+.TP
+\fB\-foreground \fIcolor\fR
+Same as the \fB\-outline\fR option.
+.TP
+\fB\-justify \fIjustify\fR
+Specifies how the text should be justified.  This matters only when
+the marker contains more than one line of text. \fIJustify\fR must be
+\f(CWleft\fR, \f(CWright\fR, or \f(CWcenter\fR.  The default is
+\f(CWcenter\fR.
+.TP
+\fB\-outline \fIcolor\fR
+Sets the color of the text. The default value is \f(CWblack\fR.
+.TP
+\fB\-padx \fIpad\fR
+Sets the padding to the left and right exteriors of the text.
+\fIPad\fR can be a list of one or two screen distances.  If \fIpad\fR
+has two elements, the left side of the text is padded by the first
+distance and the right side by the second.  If \fIpad\fR has just one
+distance, both the left and right sides are padded evenly.  The
+default is \f(CW4\fR.
+.TP
+\fB\-pady \fIpad\fR
+Sets the padding above and below the text.  \fIPad\fR can be a list of
+one or two screen distances.  If \fIpad\fR has two elements, the area above the
+text is padded by the first distance and the area below by the second.
+If \fIpad\fR is just one distance, both the top and bottom areas
+are padded evenly.  The default is \f(CW4\fR.
+.TP
+\fB\-rotate \fItheta\fR
+Specifies the number of degrees to rotate the text.  \fITheta\fR is a
+real number representing the angle of rotation.  The marker is first
+rotated along its center and is then drawn according to its anchor
+position. The default is \f(CW0.0\fR.
+.TP
+\fB\-text \fItext\fR
+Specifies the text of the marker.  The exact way the text is
+displayed may be affected by other options such as \fB\-anchor\fR or
+\fB\-rotate\fR.
+.SS "WINDOW MARKERS"
+A window marker displays a widget at a given position.
+Window markers are created with the marker's \fBcreate\fR operation in
+the form:
+.DS
+\fIpathName \fBmarker create window \fR?\fIoption value\fR?...
+.DE
+There may be many \fIoption\fR-\fIvalue\fR
+pairs, each sets a configuration option
+for the marker.  These same \fIoption\fR\-\fIvalue\fR pairs may be
+used with the marker's \fBconfigure\fR command.
+.PP
+The following options are specific to window markers:
+.TP
+\fB\-anchor \fIanchor\fR
+\fIAnchor\fR tells how to position the widget relative to the
+positioning point for the widget. For example, if \fIanchor\fR is
+\f(CWcenter\fR then the widget is centered on the point; if \fIanchor\fR
+is \f(CWn\fR then the widget will be displayed such that the top center
+point of the rectangular region occupied by the widget will be at the
+positioning point.  This option defaults to \f(CWcenter\fR.
+.TP
+\fB\-height \fIpixels\fR
+Specifies the height to assign to the marker's window.  If this option
+isn't specified, or if it is specified as \f(CW""\fR, then the window is
+given whatever height the widget requests internally.
+.TP
+\fB\-width \fIpixels\fR
+Specifies the width to assign to the marker's window.  If this option
+isn't specified, or if it is specified as \f(CW""\fR, then the window is
+given whatever width the widget requests internally.
+.TP
+\fB\-window \fIpathName\fR
+Specifies the widget to be managed by the barchart.  \fIPathName\fR must
+be a child of the \fBbarchart\fR widget.
+.SH "GRAPH COMPONENT BINDINGS"
+Specific barchart components, such as elements, markers and legend
+entries, can have a command trigger when event occurs in them, much
+like canvas items in Tk's canvas widget.  Not all event sequences are
+valid.  The only binding events that may be specified are those
+related to the mouse and keyboard (such as \fBEnter\fR, \fBLeave\fR,
+\fBButtonPress\fR, \fBMotion\fR, and \fBKeyPress\fR).
+.PP
+Only one element or marker can be picked during an event.  This means,
+that if the mouse is directly over both an element and a marker, only
+the uppermost component is selected.  This isn't true for legend entries.  
+Both a legend entry and an element (or marker) binding commands 
+will be invoked if both items are picked.
+.PP
+It is possible for multiple bindings to match a particular event.
+This could occur, for example, if one binding is associated with the
+element name and another is associated with one of the element's tags
+(see the \fB\-bindtags\fR option).  When this occurs, all of the 
+matching bindings are invoked.  A binding associated with the element
+name is invoked first, followed by one binding for each of the element's 
+bindtags.  If there are multiple matching bindings for a single tag, 
+then only the most specific binding is invoked.  A continue command 
+in a binding script terminates that script, and a break command 
+terminates that script and skips any remaining scripts for the event, 
+just as for the bind command.
+.PP
+The \fB\-bindtags\fR option for these components controls addition
+tag names which can be matched.  Implicitly elements and markers
+always have tags matching their names.  Setting the value of
+the \fB\-bindtags\fR option doesn't change this.
+.SH "C LANGUAGE API"
+You can manipulate data elements from the C language.  There
+may be situations where it is too expensive to translate the data
+values from ASCII strings.  Or you might want to read data in a
+special file format.
+.PP
+Data can manipulated from the C language using BLT vectors.
+You specify the X-Y data coordinates of an element as vectors and
+manipulate the vector from C.  The barchart will be redrawn automatically
+after the vectors are updated.
+.PP
+From Tcl, create the vectors and configure the element to use them.
+.CS
+vector X Y
+\&.g element configure line1 -xdata X -ydata Y
+.CE
+To set data points from C, you pass the values as arrays of doubles
+using the \fBBlt_ResetVector\fR call.  The vector is reset with the
+new data and at the next idle point (when Tk re-enters its event
+loop), the graph will be redrawn automatically.
+.CS
+#include <tcl.h>
+#include <blt.h>
+
+register int i;
+Blt_Vector *xVec, *yVec;
+double x[50], y[50];
+
+/* Get the BLT vectors "X" and "Y" (created above from Tcl) */
+if ((Blt_GetVector(interp, "X", 50, &xVec) != TCL_OK) ||
+    (Blt_GetVector(interp, "Y", 50, &yVec) != TCL_OK)) {
+    return TCL_ERROR;
+}
+
+for (i = 0; i < 50; i++) {
+    x[i] = i * 0.02;
+    y[i] = sin(x[i]);
+}	
+
+/* Put the data into BLT vectors */
+if ((Blt_ResetVector(xVec, x, 50, 50, TCL_VOLATILE) != TCL_OK) ||
+    (Blt_ResetVector(yVec, y, 50, 50, TCL_VOLATILE) != TCL_OK)) {
+   return TCL_ERROR;
+}
+.CE
+See the \fBvector\fR manual page for more details.
+.SH SPEED TIPS
+There may be cases where the bar chart needs to be drawn and updated as
+quickly as possible.  If drawing speed becomes a big
+problem, here are a few tips to speed up displays.
+.TP 2
+\(bu 
+Try to minimize the number of data points.  The more data points 
+looked at, the more work the bar chart must do.  
+.TP 2
+\(bu 
+If your data is generated as floating point values, the time required
+to convert the data values to and from ASCII strings can be
+significant, especially when there any many data points.  You can
+avoid the redundant string-to-decimal conversions using the C API to
+BLT vectors.
+.TP 2
+\(bu
+Don't stipple or dash the element.  Solid bars are much faster.
+.TP 2
+\(bu 
+If you update data elements frequently, try turning off the
+widget's \fB\-bufferelements\fR option.  When the bar chart is first
+displayed, it draws data elements into an internal pixmap.  The pixmap
+acts as a cache, so that when the bar chart needs to be redrawn again, and
+the data elements or coordinate axes haven't changed, the pixmap is
+simply copied to the screen.  This is especially useful when you are
+using markers to highlight points and regions on the bar chart.  But if
+the bar chart is updated frequently, changing either the element data or
+coordinate axes, the buffering becomes redundant.
+.SH LIMITATIONS
+Auto-scale routines do not use requested min/max limits
+as boundaries when the axis is logarithmically scaled.  
+.PP
+The PostScript output generated for polygons with more than 1500
+points may exceed the limits of some printers (See PostScript Language
+Reference Manual, page 568).  The work-around is to break the polygon
+into separate pieces.
+.SH KEYWORDS
+bar chart, widget