ICAO 9880 PART II PDF

OVERVIEW

The ATSMHS application, formerly known as the ATS message service, allows ATS messages to be exchanged between service users.

The ATSMHS application aims to provide generic message services over the ATN internet. It may in turn be used as a communication system by user-applications communicating over the ATN. This may be achieved, for instance, by means of application programme interfaces with the ATSMHS.

The ATSMHS is provided by the implementation over the ATN internet communication services of the message handling systems specified in ISO/lEC 10021 and CCITT or ITU-T X.400, complemented by the additional requirements specified in this manual. The ISO/IEC MOTIS international standards and the CCITT X.400 series of recommendations (1988 or later) are in principle aligned with each other. However, there are a small number of differences between these international standards and ISPs where applicable. Where necessary, for example, for reasons of interworking or to point out differences, reference is also made to the relevant X.400 recommendations.

Two levels of service are defined within the ATSMHS:

a) the basic ATSMHS; and

b) the extended ATSMHS.

The basic ATSMHS is based on the first version of the ISO/lEC ISPs, published in 1994 and based on the ISO/lEC 10021 :1990 set of standards. The extended ATSMHS is based on the third version of the ISO/lEC ISPs, published in 2003 and based on the ISO/IEC 10021 :2003 set of standards.

Both levels of service are compatible with one another. The extended ATSMHS is functionally a superset of the basic ATSMHS and is backward compatible with the basic ATSMHS.

The basic ATSMHS meets the basic requirements of the message handling systems profiles published by ISO/IEC as ISPs and incorporates additional features to support the service offered by the AFTN. The extended ATSMHS includes supplementary functions to provide a secure message service to allow for the use of the ATN directory. The ATSMHS is further specified in Chapter 3, including which ISPs apply in this context.

It is intended that the extended ATSMHS will eventually be supported by all ATSMHS users, so that the basic ATSMHS will no longer be required. However, the latter may be maintained for transition purposes as long as required.