I use ac_roofang parameter to just report the angle inside the skylight objects...(and to change the angle if used as object)
And... funfact is that the functionality kind of broke since AC 23, if the parameter is left open in parameter list...it is just skipped, like it was not there. If used in UI and the part of UI containing it is not active (not on visible page) and when the part becomes active (switching pages) - the parameter reports the default defined in the object.
Piotr