Improvements to ONS 0.3 rfc

All the implicit 1:1 relationships in the previous version have been represented as one-to-many, because users will desire to, for example, attach more than one name or GPG key with their identity.

In order to make the schema as useful as possible to as many applications as possible, all arrays and objects are generic, with object types and attributes used to attach semantic meaning to them.

This means it should be possible to create applications that can properly display an entry without needing to understand every object semantically, and application or users can add their own attributes and types as needed.

Proof has been moved to a seperate entry, which will have its own rfc. Proving identity data should also be generic, with any identity being capable of offering attestations for or against any claim made by any user.