https://posix.rhansen.org/p/gettext_draft Line 1031
"except that universal-character-name escape sequences need not be supported." Neither GNU msgfmt nor Solaris msgfmt treat universal-character-name escape sequences specially. If an msgstr contains e.g. "\\u20AC", the resulting string in the .mo file is { '\\', 'u', '2', '0', 'A', 'C', '\0' }. Issue: Leaving it undefined whether \u escape sequences are recognized can lead to mutual incompatibility of msgfmt implementations: Implementations would differ in their interpretation of the dot-po file. There is no good reason for leaving it undefined: There is already a mechanism for specifying an encoding (charset=... in the header), and the UTF-8 encoding is in widespread use for more than 10 years. Suggestion: Change "except that universal-character-name escape sequences need not be supported." to "except that universal-character-name escape sequences are not supported."