The tag-42 profile of CBOR

This document defines a bespoke serialization of CBOR intended for use with the special tag 42 in various end-to-end protocols that came out of the IPFS community. Much of its design dates to the first CBOR RFC and predates much of the terminology and the layered approach to determinism elaborated in later years. CBOR-42 can be used as an internet-scale serialization for JSON, and is optimized for objects that compose into a directed acyclical graph. Since CBOR-42 objects link to one another by hash-based identifiers tagged "42", deterministic encoding is mandated to verify dereferenced links and encode new ones.