Music score created by MuseScore, a free music composition and notation program; contains a music composition, including instruments, key signatures, music notes, and time signatures; also contains other composition information, such as the title, composer, and copyright information.

MSCX files store the uncompressed version of music scores. Compressed music scores are stored in .MSCZ files, which is the standard format for MuseScore compositions. MSCX files can be translated into twenty languages in MuseScore. Since MSCX files are saved in an uncompressed text format, they can be manually edited with any text editor. NOTE: MSCX files were introduced in MuseScore version 0.9.5 due to a file association conflict in Windows. Earlier MuseScore versions use the .MSC file extension.