Has anyone implemented some sort of methodology (or metaattribute) to indicate whether all IT services / Applicatiions (attached to a System Used attached to an Operaiotn) must be used together when performing the Operation or they can be selected indicually depending on the needs in the Operation ?
No, I haven't but I think that's because if an Operation has/can have different needs then I'm not sure it's an Operation. I'm assuming an Operation is an indivisible unit of work with "One Person, One Place, One Time" as my steer.
One could have multiple Systems Used associated to an operation, one System Used per possible set of needs, I guess.
No, in certain large companies you will find that the process, and the Operations performed are the same, but in different conuntries or Business Units they can perform the Operation using different applications or IT services.
I understand what youre saying, but in the cases you describe then they're not the same Operation. It may be a very similar Operation, but it's not the same one as it uses different tools, may take and different time, have a different cost. If any of these are different or if any of the inputs and/or outputs are different then it's not the same Operation.