Disallow empty method-specific-id in ABNF.

[peacekeeper]

Addresses #34

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Preview | Diff

[peacekeeper]

This changes the method-specific-id ABNF rule to allow leading and consecutive colons, but disallows a trailing colon or an empty method-specific-id.

E.g. allowed:

did:ex:123
did:ex::123
did:ex:sub:123
did:ex:sub::more:123
did:ex:sub::more::123

E.g. disallowed:

did:ex
did:ex:
did:ex:sub:

[msporny]

LGTM, waiting for a non-editor review before merging because it's a normative change.

[davidlehn]

#215 proposes text saying use of colons is "entirely method specific". That seems to be a slight conflict with also restricting their trailing use here.

[peacekeeper]

That seems to be a slight conflict with also restricting their trailing use here.

Thanks @davidlehn for pointing this out, I just updated #215 to reflect this. Do you agree with this change?

[davidlehn]

@peacekeeper Sure. I added related comments to the other PR.

[msporny]

Normative, multiple reviews, uncontroversial, merging.