Format/length:	an14
HES item:
National Codes:
Default Codes:

Notes:

Definition:
This provides a unique number (per sender) to identify every CDS submission.
For each CDS Interchange submitted, the CDS INTERCHANGE CONTROL REFERENCE must be incremented by 1.
The maximum value supported is n7 and wrap around from 9999999 to 1 must be supported.

Usage:
This is a mandatory data element when submitting CDS Interchanges and is used to uniquely identify and if required, to sequence check all CDS submissions.
Although EDIFACT configures a 14 alpha-numeric format, a maximum value of 9,999,999 is permitted in the format of n7.
This control reference data may also be presented on service messages and audit logs, etc.

CDS-XML Interchanges:
All CDS-XML interchanges submitted must contain a CDS INTERCHANGE CONTROL REFERENCE.

NHSCDS EDIFACT Interchanges:
The CDS INTERCHANGE CONTROL REFERENCE is represented by the data value contained in the EDIFACT UNB 0020 Interchange Control Reference data element.
EDI gateway management and translation solution sets usually generate the required EDIFACT Service Segments (UNB, UNH, UNT, UNZ).

CDS INTERFACE GATEWAY SERVICE Interchanges:
The CDS INTERCHANGE CONTROL REFERENCE is represented by the data value contained in the Control Number data element as defined in the Interface Gateway Service Control record. The authorised source of this definition is contained in the NWCS User Guide.

Note that in the CDS IGS record the Control Number data field has a format of n7.
Wrap around from 9999999 to 1 must be supported.