EDI Functional Acknowledgement Transaction Set (997) this transaction set can be used to define the control structures for a set of acknowledgments to indicate the results of the syntactical analysis of the electronically encoded documents. Although it is not specifically named in the HIPAA Legislation or Final Rule, it is necessary for X12 transaction set processing. The encoded documents are the transaction sets, which are grouped in functional groups, used in defining transactions for business data interchange. This standard does not cover the semantic meaning of the information encoded in the transaction sets.