var f = document.forms.search.elements.zip;
var zip_init_val = '';
function clear_zip() {
  if (f.value.search('-') > -1) {
    zip_init_val = f.value;
    f.value = '';
  }
}
function restore_zip() {
  if (f.value == '') f.value = zip_init_val;
}

var f2 = document.forms.search.elements.modellnr;
var modellnr_init_val = '';
function clear_modellnr() {
  if (f2.value.search('-') > -1) {
    modellnr_init_val = f2.value;
    f2.value = '';
  }
}
function restore_modellnr() {
  if (f2.value == '') f2.value = modellnr_init_val;
}