POSIX conformance question

[Olton, Chris]

When we use the -ansi flag and include string.h, strdup isn't included. I don't know the rationale for keeping POSIX out when doing this, but that's not really my question. I understand I can still have this functionality if I define _POSIX_C_SOURCE to be >= 200809, but my question is why do I have to use this version? Why couldn't I use an earlier POSIX version (e.g. 200112) which also has strdup?