[x] I suggest changing the identifier "base64-string" to "base64url-string" or "base64url-encoded-string". The current name could be interpreted ambiguously by implementers. If you want to be even more precise, I'd suggest referencing the "Base64url Encoding" definition in Section 2 of RFC 7515.
[x] Finally, in the Acknowledgments, please change "Mike Jones" to "Michael B. Jones". (My name is very common so I always include the middle initial in professional contexts to try to help with disambiguation.)
Some further comments from Mike Jones:
[x] I suggest changing the identifier "base64-string" to "base64url-string" or "base64url-encoded-string". The current name could be interpreted ambiguously by implementers. If you want to be even more precise, I'd suggest referencing the "Base64url Encoding" definition in Section 2 of RFC 7515.
[x] Finally, in the Acknowledgments, please change "Mike Jones" to "Michael B. Jones". (My name is very common so I always include the middle initial in professional contexts to try to help with disambiguation.)