function checkForm(frm) {
// checks, if all required felds are fille out
var fName="", fVal="";

	var fCnt=frm.elements.length;	// get # of form elements

	for(var i=0; i < fCnt; i++) {				// traverse all fields
		fName = frm.elements[i].name ;
		fVal = frm.elements[i].value;
		if(! fName.indexOf("r_") ) {				// required field, if name start with 'r_'
			if(fVal.length==0) {
				alert( "Please fill out all required fields." );
				return false;

			}
		}
	}

	return true;	
}