The Free On-line Dictionary of Computing (30 December 2018):
assigned numbers
The RFC STD 2 documenting the currently
assigned values from several series of numbers used in network
protocol implementations. This RFC is updated periodically
and, in any case, current information can be obtained from the
Internet Assigned Numbers Authority (IANA). If you are
developing a protocol or application that will require the use
of a link, socket, port, protocol, etc., you should
contact the IANA to receive a number assignment.
(1996-08-19)