Question about extensibility of a DID

Hi,

 

I have been trying to understand the extensibility of a DID. The example
given is about a photo service. However, I don't understand what the example
is extending. Is the example showing how to add a new type of service? If
so, where are the @context fields for the other service types in the example
DIDs ( OpenIdconnectVersion1.0Service, CredentialRepositoryService,
XdiService, AgentService, HubService, MessagingService,
SocialWebInboxService) - or should there be any?

 

Is there any way to extend the specification to add a new property to the
DID? (Something other than a service, id, authentication)

 

Thanks,

John Varga