Date   : Wed, 02 Mar 1983 00:38:00 EST
From   : Richard P. Wilkes <RICK@mit-mc.arpa>
Subject: Error-checking

There is a problem checking just the echo from the host. Many
times, the noise may only cause incorrect characters on your
receive line while the host received and retransmitted
correctly. Some attempts I've seen have tried to "fix" xmit
errors using deletes to kill the bad chars and then
retransmitting. But, if line noise was the problem, you may be
deleting correct text.  One option is to issue a line delete
and resend the entire line.  Of course, this doesn't help if a
character was garbled into a line terminator (<CR> on most
systems).

All in all, the problem is PRETTY MESSY.  Sometimes you can
tailor to the application.  But, without some type of
checksumming or CRC, you are still going to get errors thru.
And, when using something like a text editor, the protocol has
to be careful when "correcting" to take into account screen
reformatting and the like.  All in all, not a pleasant task.

Good luck. -r