This part of ISO14827 defines the format that should be used to document those end-application messages that are to be exchanged between and among central systems. The format is protocol-independent to the extent practical. For example, this one format can be used to define data exchanges that may apply to DATEX-ASN, CORBA, or other application protocols. In general, each system can be viewed as consisting of the interfaces as shown in Figure1: Figure1 System interface Key 1 application interface 2 operator interface 3 communication interface 4 database interface 5 communications cloud 6 client system 7 server system NOTE The communications cloud between the systems may be complex or simple. This part of ISO14827 deals only with the communication interface and is at a very high level. Other parts define how end-application messages can be exchanged using various application layer protocols. While this part of ISO14827 has been designed to meet the unique requirements of a TICS environment, it has been designed in a generic fashion and thus could be used for other data exchanges as well.