The PC extension is given to files associated with a specialized music notation software called Personal Composer. PC files are used to save and store music notation documents created in the program. In addition to simply editing PC files, its data can be generated with an instrument connected via a MIDI interface.

Staff Composer is a tool known from MS-DOS operating systems, but it also worked under the control of Windows systems. Currently, the program and the PC file format are rare and considered obsolete.