function isNumKeyPressed(_event) {
	if (!_event) _event = event;
	if ((_event.keyCode < 48 || _event.keyCode > 57) & (_event.keyCode != 13)) _event.returnValue = false;
}
function isNumTireKeyPressed(_event) {
	if (!_event) _event = event;
	if ((_event.keyCode < 48 || _event.keyCode > 57) && (_event.keyCode != 13) && (_event.keyCode != 45)) _event.returnValue = false;
}
function isSumPressed(_event) {
	var keynum;
	if (window.event) keynum = _event.keyCode;
	else if (_event.which) keynum = _event.which;
	if ((keynum < 48 || keynum > 57) && (keynum != 13) && (keynum != 46) && (keynum != 8)) return false;
	else return true;
}
function isTimePressed(_event) {
	var keynum;
	if (window.event) keynum = _event.keyCode;
	else if (_event.which) keynum = _event.which;
	if ((keynum < 48 || keynum > 57) && (keynum != 13) && (keynum != 58) && (keynum != 8) && (keynum != 112) && (keynum != 80) && (keynum != 32) && (keynum != 77) && (keynum != 109) && (keynum != 65) && (keynum != 97)) return false;
	else return true;
}