This Recommendation defines the Common Interchange Format (CIF) of CCITT's Specification and Description Language (Recommendation 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. Currently, the textual representation of SDL (SDL-PR) is used to interchange specifications with the disadvantage that all graphical information is 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 will improve the independence from specific tool vendors and will allow standard bodies to accept specifications in SDL-CIF irrespective of the tool they use for their internal work. This will also improve 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-PR and is based on the SDL-PR syntax and can be read and written by tools as well as users. All the constructs available in SDL‑PR are available in SDL-CIF with the exception of the macro call construct. 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.
This Recommendation first introduces SDL-CIF. Two conformance levels are defined, one at the SDL-PR level and the second including graphical information. Then 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, tools vendors that use the CIF should also identify the CIF level they comply with for their import and export functions.