function schattieren () {
	var tabelle=document.getElementsByTagName("table");
	for(i=0; i<=tabelle.length-1; i++) {
		var klasse=tabelle[i].className;
		var pos1=klasse.indexOf("fb");
		if (pos1 > -1) {
			pos1=klasse.indexOf("ab_");
			if (pos1 > -1 ) var von=parseInt(klasse.substr(pos1+3,2));
			else var von=3;
			var pos2=klasse.indexOf("fuss_");
			if (pos2 > -1 ) var fuss=parseInt(klasse.substr(pos2+5,2));
			else var fuss=0;
			var reihe=tabelle[i].getElementsByTagName("tr");
			for (j=von -1; j<=reihe.length -fuss -1; j=j+2)
				reihe[j].className="s";
		} //endIf
	} //endFor
} //endFunc