Define the fragment resolution algorithm.

[jyasskin]

https://w3c.github.io/cid/#retrieve-verification-method has

Let verificationMethod be the result of dereferencing the vmFragment from the controllerDocument according to the rules of the media type of the controllerDocument.

This spec registers application/cid as a media type for controller documents, but it doesn't specify a fragment resolution algorithm as https://www.rfc-editor.org/rfc/rfc6838.html#section-4.11 allows. Plain JSON also doesn't. I think you're aiming at the fragment resolution algorithm used by JSON+LD, but per https://w3c.github.io/cid/#context-injection, the semantics aren't meant to rely on JSON+LD being used. So, I think you need to define how fragments are dereferenced in application/cid documents.

[msporny]

Yes, good point. We hadn't done that before because we presumed JSON-LD fragment processing, but you're right, now that we don't presume that (because of the media type), we'll have to define the rules for application/cid.