Merge pull request #308 from robinbryce/robin/issue-276-receipts

Update the definition of Receipts

draft-ietf-scitt-architecture.md

@@ -228,9 +228,8 @@ Over time, an Issuer may register new Signed Statements about an Artifact in a T
 Receipt:
 
 : a cryptographic proof that a Signed Statement is included in the Append-only Log.
-Receipts are based on Signed Inclusion Proofs, such as those as described in COSE Signed Merkle Tree Proofs {{-COMETRE}};
-they can be built on different verifiable data structures, not just binary merkle trees.
-A Receipt consists of a Transparency Service-specific inclusion proof for the Signed Statement, a signature by the Transparency Service of the state of the Append-only Log after the inclusion, and additional metadata (contained in the signature's protected headers) to assist in auditing.
+Receipts are signed proofs of verifiable data-structure properties.
+The types of Receipts MUST support inclusion proofs and MAY support other proof types, such as consistency proofs.
 
 Registration: