Mac OS X Internals: A Systems Approach

9.12. XSI IPC

The Single UNIX Specification defines a set of IPC interfaces as part of the X/Open System Interface (XSI) extensions. The XSI IPC interfaces are essentially the same as the (erstwhile) System V IPC interfaces, which have been widely supported across most Unix systems, even though they were not part of any standard for a long time. Mac OS X provides system calls for the System V IPC mechanisms, namely, message queues, semaphores, and shared memory.

XSI is a superset of the mandatory requirements for conformance to POSIX.1.