The Sockets Product Standard is a precisely defined and documented set of functionality to which products can be certified. It provides a mapping between certification, the specifications, and the test suites needed to demonstrate conformance.
IBM Corporation: z/OS Version 1 Release 2 or later on z/OS V1R2 or later with: z/OS V1R2 or later Security Server and z/OS V1R2 or later c/C++ Compiler
Silicon Graphics, Inc.: IRIX 6.5 on MIPS® processor-based SGI® systems
The SCO Group, Inc.: SCO UnixWare® 7.1.3 and later for single & multiple processor systems based on IA-32 and compatible processors and conforming to PC architecture