'disabled' er rigtig nok ikke en attribut i XHTML, men det er en del af DOM.
Følgende kan valideres:
<!DOCTYPE html
PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html><head><title></title>
<style id="BasicStyle" type="text/css">
#ENABLESTYLE, #DISABLESTYLE { background:wheat; color:sienna;}
</style>
<style id="HoverStyle" type="text/css">
#LINK { font:bold 12pt lucida console;}
#LINK:hover { background:red;}
</style>
<script type="text/javascript">
function toggleStyle(bool) {
document.getElementById("HoverStyle").disabled = bool
}
toggleStyle(true)
</script></head><body>
<p><a id="ENABLESTYLE" href="#" onmouseover="toggleStyle('')" >Enable hoverstyle</a>
<a id="DISABLESTYLE" href="#" onmouseover="toggleStyle('disabled')" >Disable hoverstyle</a>
<a id="LINK" href="#">Hover Link</a></p>
</body></html>