These are "marks" that are specified in PART objects (and are called properties rather than marks). They either change how the part appears in the score or affect all of the objects in that part some way.

At the moment there's only one property, :DISTR that allows the user to distribute notes or rests across several other parts. This is done by voice so that the user may specify multiple parts for a single instrument but insert all of the events into only one of them. The user may then, for example, treat four violins as one instrument, inserting note events for all four instruments into one part and letting FOMUS's voice separating algorithm figure out how they are distributed to the actual parts that appear in the score.

The syntax of this property is given below. The PARTID argument specifies the part that notes and rests are moved to once all voices have been determined. The VOICE or VOICEFROM arguments specify which events are to be moved. VOICETO, if given, specifies the voice the events will have once they have been moved. If VOICETO isn't given, then the new voice defaults to the position of the argument in the list. (:DISTR (PRT1 2 3) (PRT2 1 4)) is then equivalent to (:DISTR (PRT1 (2 1) (3 2)) (PRT2 (1 1) (4 2)))--events in voices 2 and 3 are distributed to the part PRT1 as voices 1 and 2 while events in voices 1 and 4 are distributed to PRT2 as voices 1 and 2.