Reserved Tokens Documentation

[ja-jha]

This is a documentation request, not a bug...

https://docs.jsonata.org/simple says in part: "Field references containing whitespace or reserved tokens can be enclosed in backticks". This is great and has already been the answer a few times in querying some odd JSON documents we have. The question has come up: "What exactly are the reserved tokens that must be handled in this manner?"

We have stumbled across a few things we would not have guessed needed escaping, such as keys that start with numbers like "1Address", but are looking for a definitive list of things that must be escaped in this manner and are unable to find anything in the docs. Can this point be clarified?