Behavior

The CSS   property specifies one or more space separated URLs indicating script(s) to attach to a CSS selector. It sets the location of the DHTML (Dynamic HTML) behavior. Behaviors allow the default functionality of a given element to be extended. Using simple CSS syntax that allows script to be separated from style and content, CSS behaviors offer a fairly elegant and efficient way to re-use script code.

Values
HTML example:

 To be or not to be, that is the question.

CSS example:

blockquote { behavior:url("hilight.htc") url("#behaveBinObject"); }