I'm a little confused about the difference between references and children. I thought it was something similar to composition versus aggregation in UML, but then I realized that a concept cannot reference 0..n instances of a given concept.
Also, how do I model a 0..1:0..n relationship between 2 concepts and make sure that MPS knows about which child (or reference) is reverse of which child or reference in the target concept.
For example, back to the calculator example, a Calculator can have several InputField's, and this relationship is modeled as a child one. But what if I want to be able to navigate from an InputField to its parent Calculator. Do I model this as a child or as a reference? And in either case, how do I specify that InputField.parentCalculator is the reverse of Calculator.inputField?