Joined: 07 Nov 2005 Posts: 1105 Location: The Netherlands at Hole 19
There is no thing like single and multiple messages; you probably mean multi-segment messages. A message may contain one or more segments deviding the messages in parts; that's why you loop in your MPP for reading messages:
first the GU for the SPA
the GN for the first segment of the message
process it and read the next segment of the message till QC
after you processed the complete message insert the SPA.