I find the W3C's official [Offline Web Applications][1] specification to be rather vague about how the cache manifest interacts with headers such as ETag, Expires, or Pragma on cached assets. I know that the manifest should be checked with each request so that the browser knows when to check the other assets for updates.

If there are assets with an expiration date that is still in the future, will they be refreshed if the cache manifest is updated? Which caching mechanism takes precedence, and when?

  [1]: http://www.w3.org/TR/offline-webapps/#offline