The Networked Reference Services Question/Answer Transaction Protocol covers processing transactions for interchange of messages between digital reference domains. It defines a set of messages and associated rules of syntax and semantics for this interchange that will support processing and routing of questions and responses and packaging of other information to be exchanged. Metadata element sets needed to identify and describe key components of both question and answer data and institutional and personal data are defined, although some sets are maintained outside the standard. applied by human begins as well as by computers. Each rule is followed by illustrative examples.