SYSML17 — Make Annex E Optional but Normative

Currently Annex E of the SysML spec is called "Non-Normative Extensions" and marked "Informative". However, the content of Annex E is widely implemented and used, and recently also referred to by other submissions as normative reference. It would therefore make much sense to make the Annex E normative, but optional (via a Compliance clause). This would still leave implementers the freedom to implement Annex E, or to ignore it. However, if implemented, then it must precisely follow the specification. This would improve interoperability and exchangeability of the Annex E items, and would make the content of Annex E referable by other submission.

To achieve this change, the Annex E title and Overview sub-clause need to be changed, and an additional bullet point inserted into Clause 5.2:

"Optional extension conformance. A tool may implement the specifications of Annex E in its entirety, or implement selected specifications from Annex E at the discretion of the tool implementer. If so, then any implementation must follow the specifications provided by Annex E exactly."