Reference dimension value in tag?

[the.one]

Is there a way to get the value from a dimension (or the length of a line) in the project referenced into a tag?

What I am trying to achieve is to make a custom ceiling tag that reports the overhead clearance (ceiling to decking / overhead floor slab) in addition to the AFF value it reports already.
I gather that that value has to be placed manually, i.e. a dimension. Of course it could be a line, if it is possible to extract the length of that line instead.

Any ideas?

[patricks]

I don't see how that could be done other than manual input. Ceilings reference a particular level, and the ceiling tag reports the offset above that level only. There is no other information associated with ceilings to achieve what you want automatically.