File created by Music Publisher, a music notation application; contains the sheet music for a musical composition; specifies instruments, time signatures, notes, dynamics, and other musical score information such as the composer and title; may be played back in the software, which helps to conceptualize the music.

MUP files are used for storing and distributing digital musical compositions. They are saved in a plain text format using a proprietary syntax that represents the musical score. The files can also be revisited and refined if the composer chooses to modify the music. When the composer finishes writing the score, the MUP file can be printed to hard copy. Another feature of the Music Publisher software is the ability to transpose existing sheet music. Users can scan hard copy music to a MUP file, transpose the music, and then reprint it. NOTE: Lauriso Software replaced Braeburn Software as the developer of Music Publisher in January 2014. However, development of Music Publisher was discontinued when Lauriso Software closed its doors.