Why not require a specific ADL, choosing from among the many choices available?
Regardless of the merits, there is no consensus on any single ADL among many user communities of IEEE 1471 . There isn’t even a consensus on what the requirements for an ADL should be. There is, however, a consensus that architects should choose their notations carefully, document these choices, and be encouraged to use well-founded ADLs. The philosophy of IEEE 1471 is use the right tool for the job: use notations appropriate to addressing the architectural concerns that specifically arise for the system at hand. If this can be accomplished with a single ADL; that’s great. If other notations are needed; use them – in a principled fashion within the organizing framework provided by IEEE 1471.
