@Section
   @Title { Captions }
   @Tag { captions }
@Begin
@PP
There are options for placing captions above, below, left, and right of
captions.graphs @SubIndex { in graphs }
the frame:
@ID @OneRow @Code {
"@Graph"
"    abovecaption { This appears above }"
"    belowcaption { This appears below }"
"    leftcaption { At left }"
"    rightcaption { At right }"
"{"
"}"
}
produces
@CD @Graph
    abovecaption { This appears above }
    belowcaption { This appears below }
    leftcaption { At left }
    rightcaption { At right }
{
}
The captions may be arbitrary Lout objects, so may include
equations, {@Code "@Rotate"}, and so on.  Each caption except
@Code rightcaption is printed in the
@Code "clines @Break" style, which means that multiple lines in one
caption will be centred beneath each other.  The @Code rightcaption
option uses the @Code "lines @Break" style, in which the lines are
left justified beneath each other.  Incidentally, this example shows
what happens if there is no data.
@PP
There are options for controlling the amount of space between each
caption (when non-empty) and the frame.  Here they are with their
default values:
@ID @OneRow @Code {
"@Graph"
"    abovegap { 0.5 cm }"
"    belowgap { 0.5 cm }"
"    leftgap { 1.5 cm }"
"    rightgap { 0.5 cm }"
"{"
"    ..."
"}"
}
This is particularly important in the case of {@Code "leftgap"}, because
Lout has no idea how wide the ticks and labels attached to the y axis
are; 1.5 cm is just a wild guess and often needs adjustment.  On the
other hand, Lout does know how high the ticks and labels on the x axis
are; it allows 1.7 times the current font size for them, and
@Code "belowgap" is additional to this.
@PP
When a graph is to be presented as a centred display, it is generally
best if the centring is done with respect to the frame alone, not the
captions, ticks, and labels.  A @Code "hidecaptions" option is provided
which accomplishes this by making the left and right captions and gaps
seem to Lout to have zero width:
@ID @OneRow @Code {
"@Graph"
"    hidecaptions { yes }"
"{"
"    ..."
"}"
}
Actually @Code "yes" has been made the default value, since the vast
majority of graphs are centred displays.  In the rare cases where
this feature is not wanted (for example, if a graph appears as an entry
in a table), use {@Code "hidecaptions { no }"}.  The y ticks and labels
seem to Lout to have zero width already, so do not need to be hidden.
@End @Section
