Reference Guide

ZCOM C I/F Library Routines
ZSEND (3X)
Chapter 4 311
If Bit ZCOM_ZSEND_NOMX (0x4000) of mode is set and the request is
to a outbound-multiplexed terminal ZLU, the outbound multiplexing is
over-ridden. This results in the data being sent directly to the terminal
(instead of the multiplexing program).
The ZCOM_ZSEND_MHD and ZCOM_ZSEND_NOMX bits are intended
for use by multiplexing programs to intercept terminal messages and
build specific messages or responses as required.
They can cause strange ZCOM subsystem behavior if used improperly;
hence, they must be used with caution.
If bit ZCOM_ZSEND_LPR (0x0080) or ZCOM_ZSEND_XPS (0x0040) is
set and the request is to a terminal, then the message will be queued on
the low priority or express transmit queue, respectively. Otherwise, it
defaults to the high priority queue.
The different transmit queues allow the caller to have some control over
the order of messages being sent. The express queue is always processed
first and is not bounded by queue limit. It is intended for sending critical
control data and should never be used for normal data. The high priority
queue is subject to queue limit checks and is intended for sending normal
data. The low priority queue is processed only after all express and high
priority messages are sent and is also bounded by queue limit checks. It
is intended for sending data in a background mode. For a busy terminal,
low priority messages will not be sent until all its higher priority
activities are completed.
mhp->mrq.mrqstat - returned status (for response messages)
mhp->mrq.mrqtag - protocol tag value (for terminal ZLU only)