Re: [xml-dev] Boolean attributes in XHTML/HTML5

[David Carlisle <davidc@nag.co.uk>]

On 10/02/2012 14:02, Len Bullard wrote:
> Which doesn't answer the question why they didn't choose disabled="yes".

I wasn't involved but presumably because that would lead people to think 
that the attribute value mattered and that disabled="no" meant something 
different from disabled="yes". The point about boolean attributes as 
interpreted by browsers is that they are true if they are there (with 
any value) and false if they are not there.

so in html you have <foo> and <foo disabled> as markup, in XML where you 
need to supply a value, disabled="disabled" is valid for legacy reasons, 
disabled="" is valid because that's what people thought the syntax was 
anyway and anything else including disabled="no" acts the same way as 
disabled="" but is classed as non conforming (which only matters to 
validators not to browsers)

David


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