I'm sure this has a simple explanation (and is probably only of historical interest at this point), but ... While starting to port the Python Sybase module to Python 3, among other hurdles, I noticed that RO is no longer defined. Looking in structmember.h, I see that most of the macros defined there are missing a PY_ prefix. Given that these are macros which are likely to be used by extension modules and are thus really part of the C API, shouldn't they have PY_ or _PY_ prefixes? This file got its start in 1990, so would surely have been around for the great renaming http://python-history.blogspot.com/2009/03/great-or-grand-renaming.html. Looking at the documentation on defining new types, I saw no mention of these peculiarly named constants, though they are clearly documented. Thanks, Skip