Update json-converter-keyword-handling-rfc.md

dev-docs/RFCs/vNext/json-converter-keyword-handling-rfc.md

@@ -18,10 +18,12 @@ Users may want `type` to be interpreted as one or the other but currently can't
 
 The GeoJSON standard includes type in the top-level JSON, so most GeoJSON data sets break when ingested by the deck.gl/json API.
 
-## Proposal
+## Prior Art
+
+We should likely avoid conflicting with [JSON pointer syntax](https://www.baeldung.com/json-pointer) and JSON Paths. It seems like `_`, `__`, and `@@` would be acceptable characters. We are already using `__` in deck.gl to represent internal fields, so it seems like the least ambiguity comes from use of `@@`. 
 
-Suggestions from @ibgreen–
+## Proposal
 
-Use `__type` to indicate the Javascript `type` keyword.
+deck.gl/json will use `@@type` to indicate the Javascript `type` keyword.
 
-Additionally, add a syntax for expressions, e.g, `@=` prefix: `@=[lng, lat]`, so that we didn't need to know any information about prop types to deduce which strings to parse as expressions.
+Additionally, add a syntax for expressions, e.g, `@@=` prefix: `@@=[lng, lat]`, so that we didn't need to know any information about prop types to deduce which strings to parse as expressions.