Missing definition of _XOPEN_CURSES?

[GitMensch]

https://pubs.opengroup.org/onlinepubs/7908799/xcurses/curses.h.html says

The following constant is defined if the implementation supports the indicated revision of the X/Open Curses specification: _XOPEN_CURSES

rechecked on AIX curses.h: this says #define _XOPEN_CURSES 4002

PDCurses implements all methods mentioned above, doesn't it?

... Hm, checking the newer version X/Open Curses, Issue 7 (Reference C094) this sounds different:

The material on pages labeled ENHANCED CURSES and the material flagged with the EC-margin legend is available only in cases where the _XOPEN_CURSES version test macro is defined.

So... Should PDCurses only defines this if it implements everything, include handling the "Terminfo Source Format" and terminfo database(s)? I'm confused.