IS vs AS keywords for PL/SQL Oracle Function or Procedure Creation

Question

I have been trying to find out what the difference is between the IS and AS keywords in PL/SQL when creating an Oracle function or procedure.

I have searched and have been unable to find any information on this. Does anyone know the difference?

Answer 1

I've never known there to be a difference. The Oracle documentation implies that they are synonyms:

The function body begins with the keyword IS (or AS) and ends with the keyword END followed by an optional function name.

Answer 2

Same as DISTINCT and UNIQUE in select statements. i.e there is no material difference. Backwards compapibility and meeting standards