Purpose of asterisk before a CSS property

The following is taken from the Yahoo CSS开发者_运维知识库 reset. Can someone please explain the purpose of the asterisks?

body {
  font:13px/1.231 arial,helvetica,clean,sans-serif;
  *font-size:small;
  *font:x-small;
}

It is a browser specific CSS hack for versions 7 or below of Internet Explorer.

*property: value

Although Internet Explorer 7 corrected its behavior when a property name is prefixed with an underscore or a hyphen, other non-alphanumeric character prefixes are treated as they were in IE6. Therefore, if you add a non-alphanumeric character such as an asterisk (*) immediately before a property name, the property will be applied in IE and not in other browsers. Unlike with the hyphen and underscore method, the CSS specification makes no reservations for the asterisk as a prefix, so use of this hack could result in unexpected behavior as the CSS specifications evolve.

*property: value applies the property value in IE 7 and below. It may or may not work in future versions. Warning: this uses invalid CSS.

From: http://www.javascriptkit.com/dhtmltutors/csshacks3.shtml

It's an Internet Explorer hack. If you add a non-alphanumeric character such as an asterisk (*) immediately before a property name, the property will be applied in IE7 and below, but not in other browsers.

http://www.javascriptkit.com/dhtmltutors/csshacks3.shtml

All browsers but IE ignore the rules. It's known as the star hack. I think IE7 will ignore the rules in standards mode.

In this case, the font rule is set and then overridden for IE 6 and sometimes 7.

Placing characters like that is a hack/workaround for getting IE 6 to use a style's property, while hiding it from more "sane" browsers.

From here:

To cut a long story short, the Internet Explorer CSS parser is overly aggressive at trying to discover the names of properties and will in fact ignore leading non-alphanumeric characters. From my testing this appears to be the case from at least IE5 onwards.

As far as I know, asterisk prevents Firefox to read the attribute, but is valid in IE.

It's a CSS hack, that rule will only be applied to IE7 and below.

I wouldn't recommended using it though, there's better ways to fix IE incompatibilities.