Trick on how to parametrize an angle in a tag family. This is especially useful if we want to describe components such as stairs in a section view, where we want it to be perfectly aligned with a stair slope.
Tag stair run. Select it and go to Edit Family mode. There activate the visibility of reference planes. You may also start from scratch selecting New-> Family.
Draw reference LINE which starts in the starting point. Add an Angle Dimension and create a parameter out of it by selecting and selecting on the ribbon create parameter. (in the newer versions of Revit this option is inside ribbon on the right, in the older version it was below the ribbon). Make it a Type parameter.
Place the tag. Create -> Label . Rotate it so it matches the current angle of the reference line.
Create a group by selecting line and the tag. Groups are created under Modify Tab.
Test the family by changing the angle. If tag moves try to fix the position of it.
Load the family back into the project and adjust the angle of the tag so it matches the slope of a stair.