A rotation is specified by a percentage ratio similar to a road grade.
E.g., a 5% grade rises (or falls) 5 ft for every 100 ft of horizontal
distance ("rise over run"). To compute the percentage for a desired
rotation, pick a point of the image that is to be rotated closer to
the edge of the medium. Choose how much closer to the edge you want
that point to be, i.e., the amount that the point needs to "shift"
(e.g. .25"). Then measure the distance *along* that same edge from
the centerline of the image to that point (e.g. 27.75"). Divide the
shift by the distance and multiply by 100. (E.g. 100 x .25 / 27.75
= .9.)

A positive number causes the software to compensate by rotating the
image in a counter-clockwise direction. A negative number causes
clockwise rotation.

Profile Example (this includes split offset, but rotation tags could be used by themselves):

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE profile SYSTEM "WebGrowthProfile.dtd">

<measurePosition x = "1" y = "1" unit = "inch" />
<measureShift x = "1" y = "1" unit = "mm" />

<plate tower="1" side="U" alignX="R" offsetX="-.12" >
<expansion xpercent="0.80" />
<plate tower="2" side="U" alignX="R" offsetY="0.08" >
<expansion xpercent="0.50" />
<plate tower="3" side="U" alignX="R" >
<expansion xpercent="0.20" />
<rotation angle="1" />
<plate tower="4" side="U" alignX="R" >
<expansion xpercent="0.00" />
<rotation angle="-1" />