According to Freeman [1] the word 'protocol' comes from the Greek
proto (first) and
kolla (glue) and indicated the first sheet of a roll of papyrus whose sheets are glued together. It "listed the contents of the manuscript and its purport." The
American Heritage Dictionary [2] concurs. The reason this caught my attention is that in most network protocols the first part of a packet is generally the header, which also lists its contents.
[1] Morton S. Freeman,
The Story Behind the Word, ISI Press, Philadelphia, 1985, pp. 218-219.
[2]
The American Heritage Dictionary of the English Language, fourth edition, Houghton Mifflin Company, New York, 2006, p. 1410.