From Habari Project
- This is still a draft document
The pros and cons of using HTML or XHTML has been discussed on numerous occasions in the past and this document servers to state the official policy the Habari project has chosen to take and gives a brief example of how you can output your content using your chosen mimetype.
The Habari community has chosen to embrace HTML 4.01 Strict for all content with the view of taking full advantage of HTML 5 when it becomes an official standard. The Habari community will embrace features of HTML 5 as deemed fit as browsers improve to implement these standards whilst HTML 5 is still in the draft phase.
Due to the above stance, by default, Habari will serve HTML compliant content in all core supplied plugins and themes. Other plugins and themes can render content in their own chosen markup.
Comment Form in XHTML
Generally speaking, most of the output a user will see if governed by the theme and accordingly, it's up to the theme to produce the necessary headers, content types etc. The one exception that people may stumble on is the FormUI generated comment form. The elements are HTML compliant and not XHTML Strict compliant. In order for your comment form to be rendered as strict XHTML, you will need to implement your own formcontrols for the elements as detailed in Customising FormUI Elements.