diff --git a/man5/locale.5 b/man5/locale.5
index fdd5b9b54..b374b8f77 100644
--- a/man5/locale.5
+++ b/man5/locale.5
@@ -197,11 +197,14 @@ followed by the language name in the language of the current document.
 followed by the two-letter abbreviation of the language (ISO 639).
 .TP
 .I lang_term
-followed by the three-letter abbreviation of the language (ISO 639-2).
+followed by the three-letter abbreviation of the language (ISO 639-2/T).
 .TP
 .I lang_lib
-followed by the three-letter abbreviation of the language for
-library use (ISO 639-2).
+followed by the three-letter abbreviation of the language for library
+use (ISO 639-2/B). Applications should prefer in general
+.IR lang_term
+over
+.IR lang_lib .
 .PP
 The
 .B LC_ADDRESS