`hb_language_from_string` accepts not only ISO 639 but also BCP 47. Not
all ISO 639 codes are valid BCP 47 tags but the function does not accept
overlong language subtags anyway.
* are orthogonal to the scripts, and though they are related, they are
* different concepts and should not be confused with each other.
*
- * Use hb_language_from_string() to convert from ISO 639 language codes to
+ * Use hb_language_from_string() to convert from BCP 47 language tags to
* #hb_language_t.
*
* Since: 0.9.2
/**
* hb_language_from_string:
* @str: (array length=len) (element-type uint8_t): a string representing
- * ISO 639 language code
+ * a BCP 47 language tag
* @len: length of the @str, or -1 if it is %NULL-terminated.
*
- * Converts @str representing an ISO 639 language code to the corresponding
+ * Converts @str representing a BCP 47 language tag to the corresponding
* #hb_language_t.
*
* Return value: (transfer none):
- * The #hb_language_t corresponding to the ISO 639 language code.
+ * The #hb_language_t corresponding to the BCP 47 language tag.
*
* Since: 0.9.2
**/