+=item B<HRULE>B<:>I<value>B<#>I<color> [ :I<legend> ]
+
+Draw a horyzontal line at I<value>. HRULE acts much like LINE except that
+will have no effect on the scale of the graph. If a HRULE is outside the
+graphing area it will just not be visible.
+
+=item B<LINE>[I<width>]B<:>I<value>[B<#>I<color>][B<:>[I<legend>][B<:STACK>]]
+
+Draw a line of the specified width onto the graph. I<width> can be a
+floating point number. If the color is not specified, the drawing is done
+'invisibly'. This is useful when stacking something else on top of this
+line. Also optional is the legend box and string which will be printed in
+the legend section if specified. The B<value> can be generated by B<DEF>,
+B<VDEF>, and B<CDEF>. If the optional B<STACK> modifier is used, this line
+is stacked on top of the previous element which can be a B<LINE> or an
+B<AREA>.