The "/" at the start of the second line is a choice operator. For example, this is how you would define a term a that can match either b or c: a: b / c (T

The "/" at the start of the second line is a choice operator. For example, this is how you would define a term a that can match either b or c: a: b / c (The asterisks in my post were escaped because they were in a code block, or because there were not two of them in the same line.)