Is instr function re-entrant in VBA?

I've implemented a callback function with instr in it so far it seems working but I am asking myself if INSTR design is safe in terms of re-entrancy?

I have goggled this but I could not get a definitive answer on this

calling a global variable or access to a common resource is non-safe in re-entrant code section.

I am not certain if I could treat "instr" re-entrant safe? There's little documentation on that aspect

I'm intrigued as to what exactly you could be doing in an Excel workbook where this would possibly matter with reference to a built in function. If you're concerned about the modification of variables then pass variables byVal and don't use public