ACC X.25 Protocol User's Guide

X.25 Status and Completion Messages
Introduction
Appendix A130
Introduction
X.25 may produce a wide range of buffer status codes and unsolicited
status messages, apart from the standard communications statuses.
Most of the messages are received by the zx25d driver. The ACC X.25
driver (zx25d) may also produce error messages which will be logged to
the system error logging device by zmlog. Refer to the Multiprotocol ACC
Utilities Reference Guide for more information on zmlog. The messages
logged by the zx25d driver are explained in Multiprotocol ACC Error
Guide.
Status messages are retrieved by an application using the zread()
routine. To determine whether the message retrieved is a data message
or a status message, you must examine the ZCOM message header
returned. For example, if the variable mhdp is a pointer to the ZCOM
message header returned by zread(), then you should examine the
following fields to determine if the message read was an unsolicited
status message from the X.25 subsystem:
mhdp->mid .msty pe will contain the value
ZCOM_MSTYPE_RSLT to indicate a
response message from a local
terminal. The mhdp->mrq.mrqcode
field will further indicate what kind
of response message was read.
mhdp->m rq .mr qcode will contain the value
ZCOM_MRQCODE_STATUS to
indicate the response message
contains unsolicited status data.
mhdp->m rq .mr qcode will contain the value
ZCOM_MRQCODE_CNTWR to
indicate the response message
contains buffer completion status for
a control write request (zcntl).
Usually, this indicates an error
condition.
mhdp->m rq .mr qcode will contain the value
ZCOM_MRQCODE_WRITE to
indicate the response message