[Dev-luatex] determining if a macro is used on document level

Hi there, is there a way to determine if a macro is used on document level (in contrast of being hidden in the expansion text of some other macro)? One way that I think this could be determined is looking at the current input_stack level (which would be 1 (or 2?) inside the expansion of that macro) however while you can get at the current max stack level via status.max_in_stack I don't see any exposure of the current stack level (as a read only value). Am I missing something? Can you see any other way to determine that a macro is really used on document/file level? frank