Abbreviation for Modular Digital Multitrack. It pertains to any digital multitrack tape machine that is designed to work in conjunction with other like machines such that together they effectively build a "machine" with more tracks and/or capabilities. The Alesis ADAT and Tascam DA series machines are the most noteworthy examples, but others have been built by Fostex, Sony, Panasonic, and Studer. Compatible machines of different brands can be "linked" together under the modular environment, but otherwise they can only be synchronized together much the same way any dissimilar recorders traditionally have been.