Offset (MQLONG)

This is the offset in bytes of the data in the physical message from the start of the logical message of which the data forms part. This data is called a segment. The offset is in the range 0 through 999 999 999. A physical message that is not a segment of a logical message has an offset of zero.

The application does not need to set this field on the MQPUT or MQGET call if:

On the MQPUT call, MQPMO_LOGICAL_ORDER is specified.
On the MQGET call, MQMO_MATCH_OFFSET is not specified.

These are the recommended ways of using these calls for messages that are not report messages. However, if the application does not comply with these conditions, or the call is MQPUT1, the application must ensure that Offset is set to an appropriate value.

On input to the MQPUT and MQPUT1 calls, the queue manager uses the value described in Physical order on a queue. On output from the MQPUT and MQPUT1 calls, the queue manager sets this field to the value that was sent with the message.

For a report message reporting on a segment of a logical message, the OriginalLength field (provided it is not MQOL_UNDEFINED) is used to update the offset in the segment information retained by the queue manager.

On input to the MQGET call, the queue manager uses the value shown in Table 2. On output from the MQGET call, the queue manager sets this field to the value for the message retrieved.

The initial value of this field is zero. This field is ignored if Version is less than MQMD_VERSION_2.