Analysis of information sources in references of the Wikipedia article "POSIX" in English language version.
If you want to build single codebase C++ code to run on Windows, Linux and MacOS, you need this for Windows
librt, libposix4- POSIX.1b Realtime Extensions library [...] librt is the preferred name for this library. The name libposix4 is maintained for backward compatibility and should be avoided. Functions in this library provide most of the interfaces specified by the POSIX.1b Realtime Extension.