base-media-type
Definition
credential plus ld plus json.
Other media types of credentials are allowed by must provide either unidirectional or bidirectional transformations. So, for example, we would create credential+acdc+json and provide a unidirectional transformation to credential+ld+json.
KERI related
We are going for credential plus acdc plus json without @context. The main objection to use @context is that it can change the meaning of a credential.
The other way around: ACDCs will include W3C credentials.
Media types will be used to differentiate between types of credentials and verifiable credentials.