the biggest thing we could get for the standard that would really help people to animate TinyVG files via a secondary format, without animating TinyVG files, is if you can tag an item with a reference. Maybe do commands 17-26, which are (command n - 16) + an optional 32-bit "reference" field on the top. References are basically "up to the implementor" to do whatever they want with. You might want to also do a command "16" which is an optional "group separator", followed by a 32-bit reference that is otherwise ignored by the TVG engine.

You could probably take a hard line that once you have references, there is no need for any other extension, those are doable using references.

BTW, has someone worked on a js backfill that lets you load the file format in an image tag? I'd be happy to give it a shot with zig/wasm.

Edit: OK, I just found the polyfill.