The acronym NCP, when associated with the ARPANET, changed its meaning there over time. Originally it was an acronym for the Network Control Program - the collection of software on the hosts which implemented the protocol suite of the ARPANET. It later (once there was a second protocol suite, TCP/IP, available there) became used to refer to the original protocol suite itself. For such a meaning, the original expansion was inappropriate, so starting with RFC-772 (from September 1980), it became a backronym for Network Control Protocol.
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