Some elements of
[HTML5](http://www.whatwg.org/specs/web-apps/current-work/multipage/) can be
safely supported by ikiwiki. There are [several differences between HTML4 and
HTML5](http://www.w3.org/TR/html5-diff/).

> In the `origin/html` branch, there is an old work in progress to make
> ikiwiki use html 4 instead of xhtml. If that could be brought forward and
> finished then the plan has been to switch ikiwiki over to doing html 4.
> I don't think it makes sense to try to make it support both xhtml and
> html, it would complicate the code for no benefit.
> 
> I think that is the best route toward supporting html 5 as well. Get
> ikiwiki doing html 4 first and the changes needed to get to 5 from there
> should be small. Probably just changing some doctypes and a few other
> small changes which could be kept in a branch, or even shipped in ikiwiki
> mainline as an alternate set of templates. Some of the changes, like
> supporting new html 5 tags in the htmlscrubber, can be done in mainline.
> (Like was already done for the html 5 video and audio tags.)
>
> This approach seems much more maintainable going foward than rolling a
> html 5 branch immediatly and trying to keep that continually up-to-date
> with mainline ikiwiki that is still using xhtml. --[[Joey]]

>> TODO Still need to merge origin/html with my html5 branch.

* [HTML5 branch](http://git.webconverger.org/?p=ikiwiki;h=refs/heads/html5)
* [test ikiwiki instance with HTML5 templates](http://h.dabase.com/html5/)

# HTML5 Validation and t/html.t

[validator.nu](http://validator.nu/) is the authorative HTML5 validator,
however it is almost impossible to sanely introduce as a build dependency
because of its insane Java requirements. :( I test locally via
[cURL](http://wiki.whatwg.org/wiki/IDE), though Debian packages cannot be built
with a network dependency.

In the future, hopefully ikiwiki can test for valid HTML5 using [Relax NG
schema](http://syntax.whattf.org/) using a Debian package tool
[rnv](http://packages.qa.debian.org/r/rnv.html).

# Issues

## Time element

The [time element](http://www.whatwg.org/specs/web-apps/current-work/multipage/text-level-semantics.html#the-time-element) ideally needs the datatime= attribute set by a template variable with what [HTML5 defines as a valid datetime string](http://www.whatwg.org/specs/web-apps/current-work/multipage/infrastructure.html#valid-global-date-and-time-string).

As a workaround I use in my setup file:

	timeformat => '%Y-%m-%d',

## Header

Many of the header `<span>`s should be proper [header elements](http://www.whatwg.org/specs/web-apps/current-work/multipage/semantics.html#the-h1,-h2,-h3,-h4,-h5,-and-h6-elements)
  > See [[todo/Option_to_make_title_an_h1__63__]] for why not. --[[Joey]] 

The [header element](http://www.whatwg.org/specs/web-apps/current-work/multipage/semantics.html#the-header-element) requires a h1-h6 child, in order to [validate](http://validator.nu/). Hence in my [html5 page templates](http://git.webconverger.org/?p=ikiwiki;a=tree;f=templates;hb=refs/heads/html5), I've marked up page title with a h1.