This information was taken from the Linux Programming Guide, which is part of the Linux Documentation Project. It is possible that this collection is out of date; you can see the entire, up to date document at http://www.linuxdoc.org/LDP/lpg.
The information presented here is accurate for LINUX IPC systems, and does not necessarily reflect the status of the cygwin IPC package. There may be differences: for instance, some functions are not implemented in the cygipc package. We'd like cygipc to function just like the linux implementation; if you find discrepancies please report them (preferable with a patch to supply the missing functionality). See http://www.neuro.gatech.edu/users/cwilson/cygutils/V1.1/cygipc/ for more information.