anchor.diff:  * https://tools.ietf.org/html/rfc8473[RFC 8473]: Token Binding over HTTP
   * https://tools.ietf.org/html/rfc8586[RFC 8586]: Loop Detection in Content Delivery Networks (CDNs)
   * https://tools.ietf.org/html/rfc8594[RFC 8594]: The Sunset HTTP Header Field
  +* https://tools.ietf.org/html/rfc8673[RFC 8673]: HTTP Random Access and Live Content
  +* https://tools.ietf.org/html/rfc8674[RFC 8674]: The "safe" HTTP Preference
   * https://www.w3.org/TR/webmention/[Webmention]: Webmention
   
   ==== Upcoming
  
positive.code: * https://tools.ietf.org/html/rfc5789[RFC 5789]: PATCH Method for HTTP
  * https://tools.ietf.org/html/rfc5843[RFC 5843]: Additional Hash Algorithms for HTTP Instance Digests
  * https://tools.ietf.org/html/rfc5861[RFC 5861]: HTTP Cache-Control Extensions for Stale Content
  * https://tools.ietf.org/html/rfc5988[RFC 5988]: Web Linking
  * https://tools.ietf.org/html/rfc6265[RFC 6265]: HTTP State Management Mechanism
  * https://tools.ietf.org/html/rfc6266[RFC 6266]: Use of the Content-Disposition Header Field
  * https://tools.ietf.org/html/rfc6454[RFC 6454]: The Web Origin Concept
  
negative.code: * https://tools.ietf.org/html/rfc8187[RFC 8187]: Indicating Character Encoding and Language for HTTP Header Field Parameters
  * https://tools.ietf.org/html/rfc8188[RFC 8188]: Encrypted Content-Encoding for HTTP
  * https://tools.ietf.org/html/rfc8246[RFC 8246]: HTTP Immutable Responses
  * https://tools.ietf.org/html/rfc8288[RFC 8288]: Web Linking
  * https://tools.ietf.org/html/rfc8297[RFC 8297]: An HTTP Status Code for Indicating Hints
  * https://tools.ietf.org/html/rfc8336[RFC 8336]: The ORIGIN HTTP/2 Frame
  * https://tools.ietf.org/html/rfc8441[RFC 8441]: Bootstrapping WebSockets with HTTP/2
  