A model is a role functionally depends on certain situation in place of something else being modeled, this is what I called model as use. In any practical case, there are certain relations around a working model, which form a working system of the model. The basic elements are identified and shown in a UML class diagram below.
Note. The part of Stakeholder, System Concern, Purpose, and Environment is adopted from ISO/IEC/IEEE 42010. The term “Subject”, see the triple modeling relation; some developments to that are shown.
For you comments.