Documenting behavior adds semantic detail to elements and their interactions that have time-related characteristics. Behavioral models add information that reveals ordering of interactions among the elements, opportunities for concurrency, and time dependencies of interactions, such as at a specific time or after a period of time.
Behavior documented in the element catalog of a view and in interface specifications can be used to fill in the design background section, which includes results of analysis.
At a minimum, the stimulation of actions and transfer of information should be modelled from one element to another.
Constraints on the interaction between elements in the form of synchronous or asynchronous communication should be documented. Document any ordering constraints on actions or interactions. Document a clock if your system depends on time.
Most behavioral languages include representations of stimulus and activity, ordering of interactions, and structural elements with some relationships to which the behavior maps.
Trace-oriented models consist of sequences of activities or interactions that describe the system's response to a specific stimulus when in a specific state. They document the trace of activities through a system described in terms of its structural elements and their interactions. Use cases, use case maps, sequence diagrams, collaboration diagrams, and message sequence charts are trace-oriented modeling languages.
Static models, often state based, show the complete behavior of a structural element or set of elements. Statecharts, SDL, and Z are static behavior modeling languages.