Use of these API routines is discouraged in new application development, but they will probably hang around for quite a long time to support older applications. System V was also a de facto standard. A lot of it survived into official standards. The remainder is still around but its use is discouraged. Part 2 concerns shell programs and command-line utilities.
Certification is an expensive and time-consuming processes.
Version 2.0 of Unifix is billed as the successor to Unifix 1.2 and Linux-FT 1.2, another now defunct certified Linux effort of Lasermoon, Ltd . Linux-FT died for failing to make the jump from the 1.2.x kernels to 2.0.x. No other operating system is so tied to a programming language as Unix is to C, so any official C standard is instantly a Unix standard too. In exchange for this limited capability you get greater portability because ANSI C is available on both Unix and non-Unix systems. By owning the UNIX name, the Open Group gets to decide what products can claim the UNIX label.