CSS Syntax Question: select[class]

OK, so I am not an absolute beginner, but every now and then it feels like it.

This morning, I was reviewing somebody else's CSS code and came across the following bracket syntax:

.form_description[class]
{
	display:block;
}


select.select[class]
{
. . .

Code (markup):

Could anyone tell me what the bracketed stuff ([class]) does?

Where can I find out more about this?

Thanks.

 

That's a really weird syntax, personally I've never seen it before. Can you Pm me the url of the site you saw it on please? I am curious to check it

 

try this link on pseudo classes
http://www.w3schools.com/CSS/css_pseudo_classes.asp