Honestly, I’d be curious to understand how you understood that. I would probably argue the opposite, as in terms of methodology, you should have identified most of, if not all, your stakeholders at the OA and SA engineering perspectives. SA is where you define the boundary of your system and its interfaces with the external actors.
When you move to the LA/PA levels, you’re actually defining the solution (how the system will work to fulfill the need, and how it is going to be developed and build), in other words, your focus is to define and refine the inside of your SOI, so this is typically not the time when you would focus on discovering external actors.
Your question seems to imply that by default you are not supposed to define new capabilities at the LA/PA perspectives, or it is not possible to do so. If you follow this path, then it means that Capabilities at the LA/PA level are the sames as the ones at the OA/SA perspectives. Although this may be the case for some of them, I would be very careful in assuming this. Generally speaking, this issue here originates from the misconception that SA is a refinement of OA, LA is a refinement of SA, and PA is a refinement of LA. This is generally wrong, especially for the functional part of the model. The relationship between the engineering perspectives is REALIZATION. In other words, if you take a System Capability, at the LA level, you need to ask yourself the question: What are the Logical Capabilities of my system that are required to realize this System Capability? This answer is not a refinement of your System Capability. It is not necessarily “Sub capabilities”. If you’re just doing sub-capabilities, sub-functions, etc… between your engineering perspectives, it means that you are duplicating your model from one perspective to another and then refining it. You loose the value of the Arcadia methodology. You’d be better starting directly at the PA level and do everything in one engineering perspective, it is going to be much more effective in terms of model maintenance.
Let me give you a dummy example:
System Capability (or function) could be:
- Provide answers to customer request
Logical Capability(ies) (or functions) could be:
- Provide access to database of information to operator
- Provide means for communication with customers
- Provide tools to compose answers manually
Or they could be:
- Provide natural language interpretation of customer requests
- Provide automated retrieval of relevant data from knowledge sources
- Provide AI-generated responses to customer requests
- Provide confidence scoring for automated answers
I am just making this up, right. My point here is that these Logical Capabilities or functions are ways to realize the SA ones, not refinement.
I have explained this in a certain number of posts over the years, here’s one for example: Need guidance on Capella usage - #2 by StephaneLacrampe
I hope it helps…
Stephane