In the section on processing a bundle, the spec says:

"(...) If the server assigns a new id to any resource in the bundle as part of the processing rules above, it SHALL also update any references to that resource in the same bundle as they are processed. (...) Servers SHALL replace all matching links in the bundle, whether they are found in the resource ids, resource references, url elements, or <a href="" & <img src="" in the narrative."

We have seen that implementations differ in how this is done, especially when dealing with replacing "url elements". Replacing all elements of type "url" in general, could result in inadvertently updating canonical urls (mostly in the conformance resources), coding system urls, extension.url, Signature.whoUri and maybe others.

We need to decide whether it is best to say "replace elements of type uri in general, with these exceptions" or decide not to have a general rule for uri, and list the elements which do need to be replaced.