function tdHeight() {
	myHeight = 0;
	
	if( typeof( window.innerHeight ) == 'number' ) {
	   	myHeight = window.innerHeight;
	} else if( document.documentElement && ( document.documentElement.clientHeight ) ) {
	   	myHeight = document.documentElement.clientHeight;
	} else if( document.body && ( document.body.clientHeight ) ) {
		myHeight = document.body.clientHeight;
	}
	document.getElementById('erv4').height=myHeight-20;
}