At this stage it looks like it's primarily for hosting of known versions of libraries by CDNs. For example, https://code.jquery.com/jquery-1.9.0.min.js https://

At this stage it looks like it's primarily for hosting of known versions of libraries by CDNs. For example, https://code.jquery.com/jquery-1.9.0.min.js https://code.jquery.com/jquery-1.9.0.min.js should serve out those bytes exactly, even though there's a 1.9.1. There have been proposals for adding fallback URLs to fetch from if the primary resource fails. This way you can have your CDN and cache but fallback to a local resource too. As the spec is written currently it looks like the user will have to do this manually with an on error event. I haven't been following closely enough to see why it's taken this route. Perhaps for simplicity of the initial implementation?