When can I safely use the new element in HTML5?

Question

On the 16th December, a HTML5 extension specification for the

element was submitted to the W3C under something called an editors draft. The abstract is

Answer 1

For now, I would be careful about usng it.

For the future of the proposal, what really matters is implementation in browsers. In particular, because

is a proposed block level element, it will require a change to the HTML5 parser implementation as well as giving it the default ARIA role of main.

Without the default ARIA role, there is no point to the element, although using it now in preparation for that is a reasonable approach.

The parser change does require a modicum of care though. Remember that the

tag is optional. Now suppose you decide that before your "main" content you want a paragraph of preamble. You could write:

  
 This is my page preamble ...
  

    My main content ...
    

       A story ...
    
  

If and when browsers implement the

element, the

tag will automatically close the

element and in the DOM, the

element and the

element will be siblings of one another. The

element and its content will be a child of the

element. i.e. The DOM will be:

HTML
 +--HEAD
 +--BODY
     +--P
     |  +--This is my page preamble ... 
     +--MAIN
         +--My main content ...
         +--DIV
             +--A story 

However, right now in browsers, the

becomes a child element of the

element, and while "My main content ..." is a child of the

element, the

element is not. i.e. the DOM has this structure:

HTML
 +--HEAD
 +--BODY
     +--P
     |  +--This is my page preamble ...
     |  +--MAIN
     |      +--My main content ... 
     +--DIV
        +--A story 

Now, of course, this is easily avoided by explicitly using a

tag, on the preamble paragraph, but it is a trap for the unwary.

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