A fullword binary field. If RETCODE is
negative, the field contains an error number. See Return codes for information about ERRNO return
codes.
RETCODE
A fullword binary field that returns
one of the following values.
If COMMAND was set to 3 (query), a bit string is returned.
If RETCODE contains X'00000004', the socket is nonblocking.
(The FNDELAY flag is on.)
If RETCODE contains X'00000000', the socket is blocking.
(The FNDELAY flag is off.)
If COMMAND was set to 4 (set), a successful call is indicated
by 0 in this field. In both cases, a RETCODE of -1 indicates an error
(check the ERRNO field for the error number).