[whatwg] text/html conformance checkers and comments

[Lachlan Hunt]

Henri Sivonen wrote:
> What kinds of comments should a text/html HTML5 conformance checker allow?

All valid SGML comments should be allowed.

> <!-->

That's an incomplete comment, as it only contains a Markup Declaration 
Open (MDO "<!") and the first comment delimiter "--".  The ">" in this 
case is actually commented out and would only be valid if were later 
followed by a second comment delimiter and a Markup Declaration Close 
(MDC ">") (i.e. <!--> ... -->)

> <!---->
> <!-- -->
> <!-- foo -->
> <!-- foo ---- bar -->
> <!-- foo -- -- bar -->

Yes, all of those are supported by browsers, so there is no reason not 
too.  But you missed two other valid variants that I can think of:

<!>
<!-- -- >

As useless as the first one may be, it seems to be supported with no 
ill-effect by Deer Park Alpha 2, Opera 8 and IE6, so I see no reason to 
call it invalid.

And these invalid variants:
<! -- -->
<!-- foo -- bar -->

-- 
Lachlan Hunt
http://lachy.id.au/