Previously, we talked about urn:uuids mapping to URLs. But this is a bit imprecise, because there was actually other metadata associated with those URLs, like reporting metadata for FLEDGE reportEvent(), budget metadata for sharedStorage, etc.

This proposal makes this explicit, saying that urn:uuids map to a set of attributes, one of which is the src attribute. And we can add additional attributes like width and height that allow consumer APIs to have more control over and flexibility with information flow for their particular use case. See this document for the full proposal.

Here is an existing issue about how the proposal affects FLEDGE: WICG/turtledove#312

We welcome feedback. 🙂