RFC 117 (rfc117) - Page 2 of 5

Some comments on the official protocol

     i.  Transmit over an existent link, but connection is not
         established.
     j.  ALL or GVB on a send connection.
     k.  RET on a receive connection.
     l.  An attempt to send more than the allocated number of bits or
         messages.
     m.  ECO, ERP, ERR commands do not have the defined number of bits
        of data.

In Document No. 1, each site is supposed to document the information
on their ERR command.  No one has done that so far, and the main
reason is we are not sure of what information is important.  In
NWG/RFC No. 107, the text portion of the ERR Commands is decided to
have a fixed length of 80 bits because 80 bits is long enough to hold
the longest non-ERR command.  In some of the above error conditions,
more information than the command itself is desirable.  It was noted
that these error conditions arise very often in the experimental stage
of the NCP.  If every NCP is operating properly, none of them should
ever occur.  The ERR commands are therefore, an excellent debugging
tool for the protocol.  So it is desirable to define a set of possible
error conditions, and for each condition, define a set of arguments in
the corresponding ERR command so that enough information is given to
tell what's wrong.  The suggested arguments for each situation (a - m)
are listed below:

     a.  1.  Op. code in error.
         2.  Part of message following op. code (A maximum of 72
             bits).

     b, c, d, e, f.
         1.  The command in error.

     g.  1.  Link number,
         2.  Beginning of message (A maximum of 72 bits),

     h.  1.  Command in error.
         2.  Socket numbers for the connection.
         3.  Status of the connection.