Definition: Rewrite each original sentence in order to make it easier to understand by non-native speakers of English. You can do so by replacing complex words with simpler synonyms (i.e. paraphrasing), deleting unimportant information (i.e. compression), and/or splitting a long complex sentence into several simpler ones. The final simplified sentences need to be grammatical, fluent, and retain the main ideas of their original counterparts without altering their meanings.
Input: The Official Municipality Key, formerly also known as the Official Municipality Characteristic Number or Municipality Code Number, is a number sequence for the identification of politically independent municipalities or unincorporated areas.

The Official Municipality Key, (was known as the Official Municipality Characteristic Number), is a number order for the ID of independent cities or unincorporated areas.