what does an * (star) mean in front of a CSS rule?

Question

I'm new to CSS and am using the Yahoo YUI libraries in a project. I am learning as fast as possible, but apologize in advance if this is too rookie of a question. Can anyone help me understand the following CSS that I came across in the layout manager CSS:

I have been unable to figure out what the * (star) does to the rules (styles) in the following CSS???

.yui-skin-sam .yui-layout .yui-layout-unit div.yui-layout-bd {
border:1px solid #808080;
border-bottom:none;
border-top:none;
*border-bottom-width:0;
*border-top-width:0;
background-color:#f2f2f2;
text-align:left;
}

Thanks in advance, Bill

Answer 1

This is a hack to apply styles only to older versions of IE http://en.wikipedia.org/wiki/CSS_filter#Star_hack

Answer 2

The star exploits a bug in version 7 and below of Internet Explorer and is used to make IE render your markup correctly. More information here: http://www.ejeliot.com/blog/63