Download Metrix: A Musical Data Definition Language and Data Structure for a Spectral Modeling Based Synthesizer Since the MIDI 1.0 specification [1], well over 15 years ago, many have been the attempts to give a solution to all the limitations that soon became clear. None of these have had a happy ending, mainly due to commercial interests and as a result, when trying to find an appropriate synthesis control user interface, we had not many choices but the use of MIDI. That’s the reason why the idea of defining a new user interface aroused. In this article, the main components of this interface will be discussed, paying special attention to the advantages and new features it reports to the enduser.