Does "Copyright Claimant" Mean Singular or Plural?

Dear Rich: I have a question regarding registering a group of songs. Circular 50 states that a group of unpublished songs can be registered on one application as long as "the copyright owner or owners" is the same for all songs. Circular 50 also says that a group of published songs can be registered with one application if all the compositions are "owned by the same copyright claimant." Does "copyright claimant" mean that it must be singular -- one individual or one entity -- or can it be co-owners as long as long as all the compositions are owned by the same co-owners? We called the Copyright Office and an information specialist informed us that a copyright claimaint could be plural (co-owners) as long as the co-owners are the same for all compositions. By the way, if you're willing to stay on hold for a while, you can always get answers to copyright questions at 202-707-5959 (or toll free at 877-476-0778). If you're willing to wait, you can get written responses within 5 working days here.