Solutions
-
phjvh's post in Converting by a switch the HSI compass indicator was marked as the answerThe code i use is just a number in the HSI!
For the rotation try, not tested:
<Rotate>
<Value>
(L:href,bool)
if{ (A:PLANE HEADING DEGREES TRUE,degrees) }
els{ (A:PLANE HEADING DEGREES MAGNETIC,degrees) }
</Value>
</Rotate>