https://docs.oracle.com/cd/E88353_01/html/E37853/xns5-7.html
XNS5 - man pages section 7: Standards, Environments, Macros, Character Sets, and Miscellany
standards , ANSI , C , C++ , ISO , POSIX , POSIX.1 , POSIX.2 , SUS , SUSv2 , SUSv3 , SUSv4 , SVID , SVID3 , XNS , XNS4 , XNS5 , XPG , XPG3 , XPG4 , XPG4v2 ,...
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