Red Book

This CCITT standards committee document specifies some 1984 data communications standards that were somewhat widely used before the Internet became popular. It is "Fascicle VII.3" of "Volume VIII" of a very wordy, voluminous, hard to read set of standards. Written in international bureaucratese for telco manufacturers. No wonder the Internet took over -- you could read its standards and actually understand how it worked, unlike these. The big kahuna in this book is "X.25" which was the interface used to a bunch of connection-oriented packet-switching networks that preceded the Internet. This was particularly used in Europe, but also saw use elsewhere.