Help With Rolls JSON

If I parse the json coming back from a roll, I see content specified like this: "{\"type\":\"V\",\"rolls\":[{\"type\":\"R\",\"dice\":1,\"sides\":20,\"mods\":{},\"results\":[{\"v\":1}]},{\"type\":\"M\",\"expr\":\"+4\"}],\"resultType\":\"sum\",\"total\":5}" What does type V or R or M mean? 

There's no specific guidance on this that I'm aware of, but you can kind of infer them. V is a Value, seems to be the top level for any given formula. M is a Math operation, which can include a constant, like +3 R is a Roll, where dice were involved, like 3d6 L is a Label, like [Strength] G is a Group, like {3d6, 2d5} Those are all I can think of right now.  There might be a few others, but I don't think so.

Awesome. Thanks, Aaron!