[link|http://www.w3.org/TR/REC-CSS2/selector.html|http://www.w3.org/TR...SS2/selector.html]
You know you're going to read the whole document anyway...might as well start now. :)
Selection is done completely *before* the parameter block {}.
h1 a:link {} means "apply {} to all a:link's which are children of an h1 element".