Posix.21 is the
IEEE P1103.21 Working Group on "Realtime Distributed Systems Communication."
ftp to ftp.sei.cmu.edu
login as anonymous, password your email address.
In the directory /pub/posix is all the material related to POSIX.21.
in the /pub/posix/docs/LIS directory are the versions of
the language independent specification documents including the
latest version N109R6.ps.
There will be a new version before the July meeting,
which as expected, will be the same week as the MPI meeting in Nashua N.H.
The latest requrement document is the /pub/posix/docs/N008R10_int_req_97.ps.
The models are in /pub/posix/docs/Models/
Good luck,
Arkady