In a 277 is a comma a valid character in the claims status code; for example the comma after 232: STC*A3:232,XXX:
No, the STC01-2 data element only allows for a single Status Code from either the Health Care Claim Status Code list (Code Source 508) or the National Council for Prescription Drug Programs Reject/Payment Code list (Code Source 530). Sending additional Status Codes requires a separate STC segment for each Status Code.