CDS MESSAGE HEADER
CDS Interchanges submitted or received must use the correct CDS Header and Trailer Controls to provide Interchange and Message addressing and identification.

Every CDS Interchange must consist of:
CDS INTERCHANGE HEADER - Mandatory - One per CDS Interchange
CDS MESSAGE HEADER - Mandatory - One per CDS Message
CDS MESSAGE DATA - As defined for the specific CDS Type
CDS MESSAGE TRAILER - Mandatory - One per CDS Message
CDS INTERCHANGE TRAILER - Mandatory - One per CDS Interchange

Multiple CDS messages are usually sent in a single CDS Interchange.
Multiple CDS Interchanges may be sent in a single network transport session.

The CDS MESSAGE HEADER signifies the start of each CDS Message and contains control information for the Message.

Opt Data Element Note
M CDS MESSAGE TYPE  
M CDS MESSAGE VERSION NUMBER  
M CDS MESSAGE REFERENCE