It seems to be common consensus that for XHTML attributes which do not require any value, we should repeat the attribute name. E.g. <input disabled> in correct XHTML is <input disabled="disabled"/>.
However, we can get the HTML <input> element to be disabled using any of the following:
<input disabled=" "/><input disabled=""/><input disabled="asdfg"><input disabled="false">
Is there actually an official rule to use disabled="disabled"? Or is it a matter of taste?