Translations:Manual:$wgDummyLanguageCodes/8/en

This global variable contains an array of language codes that don't have a corresponding set of translated system messages and never will.
 * In most cases they simply map directly to another language code. These codes are left over from renames, or other legacy things.
 * "qqq" is a dummy "language" for documenting messages.
 * "qqx" (since ) is a dummy "language" that can be used with "&uselang=qqx" to view the message names in the interface.