Strange Error: unknown variable/constant "{UNSEC0000}" detected

When I compile my script, at the very end it says:

4 warnings:
unknown variable/constant "{UNSEC0000}" detected, ignoring (macro:SelectSection:3)
unknown variable/constant "{UNSEC0000}" detected, ignoring (macro:SelectSection:5)
unknown variable/constant "{UNSEC0000}" detected, ignoring (macro:UnselectSection:3)
unknown variable/constant "{UNSEC0000}" detected, ignoring (macro:UnselectSection:5)

What does this mess mean? It doesn't even provide line numbers for reference.

Neither Google nor a forum search for any of the message returned any help.