Add text clarifying where group controllers might be listed.

[msporny]

This PR is an attempt to address issue #839 by adding text clarifying where group controllers might be listed.

---

Preview | Diff

[wip-abramson]

Suggested change

	digital signatures ("m-of-n"). The expression of these additional thresholds for
	digital signatures ("m-of-n"). These additional thresholds for

[wip-abramson]

Suggested change

	[=verification method=] where the number of [=DID controllers=] that
	verification material of the [=verification method=], where the number of [=DID controllers=] that

[wip-abramson]

I also am hesitant at the use of DID controllers here.

Definition:

An entity that has the capability to make changes to a DID document. A DID might have more than one DID controller. The DID controller(s) can be denoted by the optional controller property at the top level of the DID document. Note that a DID controller might be the DID subject.

If we substitute for the definition I don't think it makes sense:

verification material of the [=verification method=], where the number of "entities that have the capability to make changes to a [DID document]" that participated in the generation of a particular digital signature are hidden for privacy reasons.

This is really the number of signing parties/entities that participated in the generation of a particular digital signature ...

Or something like that.

[wip-abramson]

Reading over the section referenced in issue #839 - https://www.w3.org/TR/did-1.0/#group-control.

I think I would add another sentence:

Verification methods that require the combination of cryptographic operations from members of a group to produce a proof MAY be used to control the contents of a DID document, how this is realized is dependent on individual DID method specifications.

Just because a DID document expresses a verificationMethod, does not automatically mean that those who can create proofs associated with that verificationMethod have the ability to control the content of the DID document. Sometimes, even often, these are completely separated by the DID method.

[TallTed]

Maybe?
Verification methods that require a proof be produced by a combination of cryptographic operations performed by members of a group MAY be used to control the contents of a DID document; exactly how this is realized depends on individual DID method specifications.