To negotiate session control and file transfers with the remote end, uucico uses a set of standardized messages. This is often referred to as the high-level protocol. During the initialization phase and the hangup phase these are simply sent across as strings. However, during the real transfer phase, an additional low-level protocol is employed which is mostly transparent to the higher levels. This is to make error checks possible when using unreliable lines, for instance.
Thu Mar 7 23:22:06 EST 1996