When setting the value of certain numeric properties (like
"width" and "radius") you can specify either an absolute
amount, or a percentage relative to the current setting.
So, for example, you can say:
box width 2.3cm
To create a box with a width of 2.3 centimeters - an absolute amount.
Or, if the current "boxwid" variable value is 2.0cm, then you could
do the same by saying:
box width 115%