function clear_fields(form_el) {
	form_el.TI.value = "";
	form_el.AU.value = "";
	form_el.CI.value = "";
	form_el.PY.value = "";
	form_el.SB.value = "";
	form_el.SS.value = "";
	form_el.PU.value = "";
}

function check_all(form_el) {
	for (var i=0; i<form_el.kataloge.length; i++){
		form_el.kataloge[i].checked = true
	}
}

function uncheck_all(form_el) {
	for (var i=0; i<form_el.kataloge.length; i++){
		form_el.kataloge[i].checked = false
	}
}

function check_catalog(form_el,name,val) {
	for (var i=0; i<form_el.kataloge.length; i++){
		if (form_el.kataloge[i].value == name) form_el.kataloge[i].checked = val
	}
}