<html><body><div style="color:#000; background-color:#fff; font-family:times new roman, new york, times, serif;font-size:12pt">Sytel asked what an ARPAnet message looked like. A few people talked about the specification for message exchange between a Host and an IMP in BBN Report 1822.<br><br>One level up from that is the specification of message exchanged between Network Control Programs in the Hosts. These were specified by the Host-Host Protocol. The Host-Host Protocol specification did not get put in the RFC series at the time, but can now be found in RFC 6529.<br><br>Other protocols built on top of the Host-Host Protocol (eg TELNET, FTP, RJE) were documented in the RFC series at the time.<br><br>Alex<br></div></body></html>