web+: enabling websites to expose services with custom URI schemes to registerProtocolHandler.

Following the morning discussion, here are the links to the web+
definition:

http://www.w3.org/TR/html5/system-state-and-capabilities.html#custom-handlers
  look for the item on scheme (registerProtocolHandler() only)

http://www.w3.org/TR/html5/iana.html#web-scheme-prefix
  Note that the Working Group is about to decide that this section needs
rewrite because it must not look like an IANA registration.

I also suggest to look at the rational section of a change proposal
related to this:
 http://www.w3.org/html/wg/wiki/User:Eoconnor/ISSUE-189#Rationale

Philippe