In telecommunications, the term protocol-control information (PCI) has the following meanings:
The queries and replies among communications equipment to determine the respective capabilities of each end of the communications link. For layered systems, information exchanged between entities of a given layer, via the service provided by the next lower layer, to coordinate their joint operation.
References
This article incorporates public domain material from Federal Standard 1037C. General Services Administration. Archived from the original on 2022-01-22.