ETYM French protocole, Late Lat. protocollum, from Greek, the first leaf glued to the rolls of papyrus and the notarial documents, on which the date was written; protos + kollan to glue.
1. Forms of ceremony and etiquette observed by diplomats and heads of state.
2. Code of correct conduct.

(Computer science) Rules determining the format and transmission of data; SYN. communications protocol.
In computing, an agreed set of standards for the transfer of data between different devices. They cover transmission speed, format of data, and the signals required to synchronize the transfer. See also interface.
A formal definition that describes how data is to be exchanged.
Preliminary draft of treaty; collection of formulae; rules of procedure and etiquette of state ceremonies, diplomatic exchanges, etc.