Vehicle DID structure

[johnx25bd]

Proposal to include an additional field in the DID for vehicles, indicating vehicle type.

This could be used as a condition in smart contracts, and to enable more sophisticated visualization in the browser.

Thoughts?

* "@context": always the same as above. 
 * "created": timestamp of when the DID is created. 
 * "entity": can be "device", "company:company name", or "individual". 
* "vehicleType": "car:ev", "car:hev", "commercial:lorry", "ship:container", "ship:tanker", etc.
 * "creator": optional, only used if its a device DID. 
 * "imei": optional, only use if its a pebble tracker

[jason-james]

Yeah let's do it.

Btw, we are being liberal with the DID document at this point, I'm not sure that we are 'permitted' by the DID spec to have extra fields like imei, entity, vehicleType in a DID document, they are probably more suited to a "verifiable claims" JSON, but I can't find any reference to where a verifiable claims document will be stored and how to link it to a DID.

But its a hackathon and a new concept so I'm comfortable doing it this way for now..