From the point of view of OMS, the composer/score/performer are of minor interest. This is because OMS is concerned primarily with the experience of music; whereas composer/score/performer are mainly about how music is produced.
This is not to say that composer/score/performer are unimportant for a total understanding of music. Rather, it is to say that OMS is a model with certain approximate boundaries; and there are certain factors in music that are somewhat outside of its boundaries.
We had considered expanding the scope of OMS to deal directly with composer/score/performer; but this seems to be a very different kind of subject matter. So for now at least, we will simply acknowledge that fact and focus on the central aspect of OMS – which is the experience of music.
That being said, OMS does have some observations to contribute re the subject of composer/score/performer:
 In the present day, there is an additional very important factor in how music is produced, and that is often called the producer . This is the person(s) responsible for the specific way in which a performance is delivered to a listener: The performance space, acoustical details (amplification, sound absorption, …), topology (physical positions of performers and listeners), programming, program notes, ambience, management of audience expectations, and so on. It seems there is much greater appreciation now than in the past of the influence of factors like this on a listener’s experience.