"Claim" is an application for benefits provided by an insurance carrier. Individuals must file a claim so that the provider of a service can get paid by the insurance. Insurance company may or may not approve a claim. Often the service providers (doctors,
hospitals) file the claim on behalf of the patient.
If you are referring to "SupLOS" in the Claims data set - my understanding is the value indicates whether the LengthOfStay field is NULL due to de-identification or because of some other reason.
Hope this helps