In the HIPAA regulations, the Secretary of Health and Human Services (HHS) adopted certain standard transactions for Electronic Data Interchange (EDI) of health care data. These transactions are:  claims and encounter information, payment and remittance advice, claims status, eligibility, enrollment and disenrollment, referrals and authorizations, coordination of benefits and premium payment.  Under HIPAA, if a covered entity conducts one of the adopted transactions electronically, they must use the adopted standard– either from ASC X12N or NCPDP (for certain pharmacy transactions)  Covered entities must adhere to the content and format requirements of each transaction. (Quelle: http://www.cms.gov/Regulations-and-Guidance/HIPAA-Administrative-Simplif...)