[whatwg] status of html5 Custom scheme and content handlers?

[brg]

RE: 6.8.2

I ask because I am interesting in providing an implementation, and am
wondering if it is stable enough to start.  It is currently marked as
a Working Draft, although I can not find any discussion since late
spring, 2009.  It reads as if the spec is fairly complete to provide
an experimental implementation, but perhaps could use a list of
forbidden schemes (eg.http, https, file).

Thanks.