function externalLinks() {
    if ( !document.getElementsByTagName ) return;
    var anchors = document.getElementsByTagName( "a" );
    for ( var i = 0; i < anchors.length; i++ ) {
        var anchor = anchors[i];
        if ( anchor.getAttribute( "href" ) && anchor.getAttribute( "rel" ) )
            anchor.target = anchor.getAttribute( "rel" );
    }
}