When developing HTTP-related software it was always driving me mad that *each* author must have had come up with their own way of formatting parameters in the HTTP headers.

For example HSTS uses semicolon:

Strict-Transport-Security: max-age=63072000; includeSubDomains; preload

but then Expect-CT uses comma:

Expect-CT: max-age=600000, enforce

Now RFC 8941 brings some order to this mess:

https://www.rfc-editor.org/rfc/rfc8941.html