The problem is, in the table there is no mentioning about the special type of label. It just said the label can be "any string".

But then you will know that the compiler will automatically infer the type based on label. So when you write something like "<f0> |<f1> G|<f2> ", it's not a regular shape, but a record.

So I have to read every page of the document to see what it does. I'm expecting some kind of briefing to let me know the features and then I can dive into it if I need it.