Due to its nature it can be used to represent simulation systems [1] without ambiguity and with a graphical notation.
[2] The language is formally complete,[3] so it can be used for code generation for either simulation or final targets.
The Specification and Description Language covers five main aspects: structure, communication, behavior, data, and inheritance.
This version is accompanied by a UML-Profile: ITU-T Recommendation Z.109 (04/12), SDL-2010 combined with UML.
Each process agent is a state machine that contributes to the action carried out by the system.
Signals received by a process agent are first placed in a queue (the input port).
A process agent is allowed to contain procedure types so that the same actions can be invoked from different places.
SDL Abstract Data Types (ADT) support basic data types such as INTEGER, REAL, CHARSTRING as well as structured ones such as structures (STRUCT), enumerated (LITERALS), constants (SYNONYMS).