Summary

This Recommendation defines the Common Interchange Format (CIF) of Specification and Description Language (ITU-T Rec. Z.100 – SDL). The CIF is intended for the interchange of graphical SDL specifications (SDL-GR) made on different tools that do not use the same storage format. Prior to the definition of CIF, the textual representation of SDL (SDL-PR) was used to interchange specifications with the disadvantage that all graphical information was lost, making the same specifications often look very dissimilar in different environments. With the CIF, this disadvantage is reduced to a minimum, as it contains most of the graphical information. The CIF improves the independence from specific tool vendors and allows standards bodies to accept specifications in SDL-CIF irrespective of the tool they use for their internal work. This also improves productivity by allowing specifications to be made on the accustomed tool. All SDL tool vendors are encouraged to provide facilities for importing and exporting SDL-CIF.

This Recommendation defines how SDL descriptions can be stored in order to be interchanged between tools coming from different vendors. It does not take into account the MSC notation. SDL‑CIF is an extension to SDL. CIF is based on the SDL-PR syntax, the textual Phrase Representation of SDL also defined in this Recommendation. CIF can be read and written by tools as well as users. All the constructs available in SDL can be expressed in graphical form or in the purely textual SDL-PR form. Constraints on graphical presentation are expressed in CIF by adding specific annotations to SDL-PR. As a result, most SDL-PR descriptions are legal SDL-CIF descriptions. SDL-CIF is an open storage format as it includes a mechanism of tool-specific directives. This mechanism allows a CIF-compliant tool to extend the format by adding specific information. SDL‑CIF is also easily implementable and provides tool vendors with two levels of tool conformance and concepts of mandatory and optional directives.

SDL-PR is an alternative text-only syntax for SDL. Before 2002, SDL-PR was published as part of Z.100, but as the main use of this notation is for communication within and between tools the definition has been moved to this Recommendation. SDL-PR is Level 0 CIF and allows the interchange of syntactically complete SDL descriptions, usually as a single file per system. Conformance to SDL-PR requires the model to conform to the corresponding semantics defined in ITU‑T Rec. Z.100.

This Recommendation introduces two further levels of SDL-CIF. Two further conformance levels are defined, one at a more liberal SDL-PR level and the second including graphical information. The complete grammar is described with the related semantics. Mandatory and optional directives are described, as well as the format for tool-specific directives. Current tool-specific directives are described in Appendix I.

Two levels of CIF conformance are defined as level 1 and level 2. Level 1 is very close to SDL-PR, but it supports incomplete SDL specifications. Level 2 includes level 1 and is able to capture most of the graphical information of SDL‑GR diagrams. A CIF specification must identify which of the two levels it complies with. Similarly, tool vendors that use the CIF should also identify the CIF level they comply with for their import and export functions.