[jmilloy]

I think the confusion may be whether you're talking about the queries or the engine. I think this change to the engine/parser would be backwards compatible because old queries will still work on the new engine. A change to the queries in a codebase to include trailing commas would not be backwards compatible because it won't work on older parsers. It seems clear to me that the change discussed here is the engine, hence it should properly be characterized as "backwards compatible".