Incidental and theme music is that music which appears extra-diegetically in the soundtracks of DWU related shows. That is to say, the audience hears the music, but the characters do not. Examples are "Song for Ten" and the Doctor Who theme itself.

The following suggestions guide organisation of other types of song:

• If it was in a DWU story and appeared to be heard, sung or referenced by characters in the narrative, but originated in the DWU — like "The Ballad of the Last Chance Saloon" — it's best put in Category:Songs.
• If it was in a DWU story and appeared to be heard or sung by characters in the narrative, but originated in the real world — like "Toxic" — it's best put in Category:Songs from the real world. If purely instrumental, like "Colonel Bogey March", it should go in Category:Instrumental compositions from the real world.
• If it was not featured in any way in an episode, but was strictly a merchandising tie-in — like "Who is the Doctor" — then it belongs to Category:Songs about the Doctor Who universe.