A Microsoft Windows Internals And Graphic Design

POSIX (Portable Operating Systems Interface) is the name used by group of standards sponsored by the IEEE that define a standard API for UNIX-like operating systems. POSIX.1 (IEEE Std1003.1-1990) standardizes the API for C. POSIX.2 (IEEE Std1003.2-1992) standardizes the shell and basic utilities. Other POSIX standards cover Ada and Fortran bindings, real time extensions, conformance testing, etc.

https://www.netbsd.org/about/standards.html