502—Allowance of claims or interest (general section)
(i)    (a) A creditor will file a claim, and if there is no objection from a party in interest, the claim is allowed.  Since under this section, it will be the allowed unsecured claim.  (If someone objects the burden is on the creditor to prove the claim.)
(ii)    (b)—the court will allow a claim, except for things listed—like post-pet interest.