key_char_traits — A char traits type that reflects the OS rules for string representing environment keys.
// In header: <boost/process/v2/environment.hpp> typedef implementation_defined key_char_traits;
Can be an alias of std::char_traits. May only be defined for char and wchar_t.
char
wchar_t
Windows treats keys as case-insensitive yet perserving. The char traits are made to reflect that behaviour.