J.4 Locale-specific behavior
The following characteristics of a hosted environment are locale-specific and are required to be documented by the implementation:
Additional members of the source and execution character sets beyond the basic character set (5.2.1).
The presence, meaning, and representation of additional multibyte characters in the execution character set beyond the basic character set (5.2.1.2).
The shift states used for the encoding of multibyte characters (5.2.1.2).
The direction of writing of successive printing characters (5.2.2).
The decimal-point character (7.1.1).
The sets of characters tested for by the isalpha, isblank, islower, ispunct, isspace, isupper, iswalpha, iswblank, iswlower, iswpunct, iswspace, or iswupper functions (7.4.1.2, 7.4.1.3, 7.4.1.7, 7.4.1.9, 7.4.1.10, 7.4.1.11, 7.25.2.1.2, 7.25.2.1.3, 7.25.2.1.7, 7.25.2.1.9, 7.25.2.1.10, 7.25.2.1.11).
The native environment (7.11.1.1).
Additional subject sequences accepted by the numeric conversion functions (7.20.1, 7.24.4.1).
The collation sequence of the execution character set (7.21.4.3, 7.24.4.4.2).
The contents of the error message strings set up by the strerror function (7.21.6.2).
Character mappings that are supported by the towctrans function (7.25.1).
Character classifications that are supported by the iswctype function (7.25.1).