+ * Since CiviCRM 4.5, expected dir structure is civicrm/l10n/xx_XX/LC_MESSAGES/civicrm.mo
+ * because that is what native gettext expects. Fallback support for the pre-4.5 structure
+ * was removed in CiviCRM 5.51.
+ *
+ * CiviCRM 5.23 added support for the CIVICRM_L10N_BASEDIR constant (and [civicrm.l10n])
+ * so that mo files can be stored elsewhere (such as in a web-writable directory, to
+ * support extensions sur as l10nupdate.
+ *