**Problem:** Language is a term I don't know how to use. I don't understand the relationship between a language and a model. Nor between a program and a model.
**Therefore:** I will narrow the search to the types of languages I am interested in.
The line between general-purpose languages and domain-specific languages is not always sharp, as a language may have specialized features for a particular domain but be applicable more broadly, or conversely may in principle be capable of broad application but in practice used primarily for a specific domain.
https://en.m.wikipedia.org/wiki/Domain-specific_language HEIGHT 500