<!-- Hide script from older browsers


function validSerialnumber(f) {

	var serial_number = f.value

                invalidCharacterz = ",@;:()=+ "
                
            if (serial_number == "") {
            alert("Hey! Let's have a serial number entered here. Please enter your unit's serial number.");
	    	frm.serial_number.focus()
		frm.serial_number.select()
		return false;
		}

        for (i=0; i<invalidCharacterz.length; i++) {
// does it contain any invalid characters?
            badCharacterz = invalidCharacterz.charAt(i)
            if (serial_number.indexOf(badCharacterz,0) > -1) {
 
		   alert("Manley and Langevin serial numbers do not contain spaces or non-alphanumeric characters. Please just enter your unit's serial number. This webform is for people who already own Manley and Langevin products. So type in your serial number, please. If you need help with a general question and you do not already own our gear, please just email us instead from our email page.");
				frm.serial_number.focus()
				frm.serial_number.select()
                     return false;
		}
		}
}
		// End hiding script -->