Does the Unity web plugin use Etags when re-downloading content?

My experiments suggest that the .unity3d file is re-downloaded every time it is requested, and that etag’s are not passed to the server. If etag’s are not supported, what HTTP caching mechanisms are?

The plugin asks the web browser to download content that it needs. The plugin does not download anything. Content fetched by the browser should be cached in the regular browser cache, assuming the server has cache control set correctly.