I'll go along with the "clearance limit" part, but I don't know about the
"airport" bit. I've certainly gotten pop-ups to climb or descend through a
cloud layer, "Cleared to the XYZ VOR".

You are correct. However in most cases it is very good to have an
airport be a clearance limit.

Jose
--
"There are 3 secrets to the perfect landing. Unfortunately, nobody knows
what they are." - (mike).
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