https://posix.rhansen.org/p/gettext_split says (line 217):
"All of the functions in the gettext family of functions, except dcgettext(), search for messages objects only in the LC_MESSAGES category." dcgettext_l, dcngettext, dcngettext_l also search in the specified category. Suggested wording: "All of the functions in the gettext family of functions, except for dcgettext(), dcgettext_l(), dcngettext(), and dcngettext_l() search for messages objects only in the LC_MESSAGES category." Bruno