What's the difference between and in SysML?

ReqIF Academy Forums Other What's the difference between and in SysML?

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    • #2188
      C R

      I hope, that despite this being a ReqIF forum, perhaps some requirements expert could explain. I just read in the SysML standard that there is a <<refine>> stereotype. Here is the definition:

      The Refine stereotype specializes UML4SysML Refine and DirectedRelationshipPropertyPath to enable refinements to identify their sources and targets by a multi-level path of accessible properties from context blocks for the sources and targets.

      Even as a native speaker, this did not make sense to me. How is this different from <<deriveReqt>> which has a clearer definition? They do show an example where a use-case <<refine>>’s a requirement. On the same diagram however, they have a requirement that has a depedency <<derivedReqt>> to the same requirement (see Figure 16.3 – Links between requirements and design of the latest standard).

    • #2189
      Michael Jastram

      Hi CR,

      First, I think that there are indeed better forums for this question than this one (see below): While ReqIF has traces (SpecRelations), ReqIF does not make any call on the semantics of the relationship. In other words, you can name relations whatever you like, and give it whatever meaning you like. As you noted correctly, this is quite different from modeling languages like SysML, which have a clearly defined semantics.

      I remember the argument of refine vs. derive from over ten years ago! One can argue one way or another, and it’s certainly arguable whether the current definition is a good idea or not (there is no right or wrong, just better or worse).

      Therefore, I am not even trying to answer your question. Instead, I would encourage you to engage with the OMG SysML Working Group:


      If you are a member of INCOSE (or a local chapter thereof), then one of their working groups would also be a good place to discuss this.

      Good Luck!

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