Developed in cooperation with the Recording Industry Association of America (RIAA) and National Music Publishers Association (NMPA), the free software facilitates the exchange of sound recording, publishing data, and ownership claims between record labels and music publishers. Basically, MDX is all about bringing more efficiency and transparency to the process of connecting recording data to publishing data.
Source: As the Music Modernization Act Nears Passage, SoundExchange Releases the ‘Music Data Exchange (MDX)’