File Extension MMD File Format mAirList metadata MMD stands for mAirList metadata. This was last updated in March 2012 By Margaret Rouse Browse File Extensions Alphabetically: A B C D E F G H I J K L M N O P Q R S T U V W X Y Z # Ask a Question. Find an Answer. Ask your peers a question about this file extension. Ask a Question The difference between GLC-SX-MM and GLC-SX-MMD How to import or add metadata in a microstrategy report? How is metadata used in the real world?