constants and braces in the execution order notation?

In my model, the execution order on my switch blocks have one or two numbers in curly braces following the regular notation. For example, a manual switch is annotated 0:2{2,1}. There is no mention in the documentation's table of "Sorted Order Notation" of braces.

In addition to this notation only appearing on switch blocks (in my small model), I notice that the constants associated with those switches have the same numbers as appear in braces, and are NOT numbered according to the scheme that everything at the top-level start with 0: etc.

What do the braces and unusual numbering of constant blocks mean? I have the various coders installed--is it something to do with code generation? (I hadn't seen this notation before, but I've not done very many models yet.)