function SWAP(einh, elm, dir, strt, trg) {
  var obj = {
    acre  : 4046.8564224, //qm
    pound : 453.59, //g
    foot  : 0.3048, //m
    inch  : 2.54, //cm
    kn    : 1.852, //kmh
    meile : 1.609344, //km
    ounce : 28.349523125 //g
  }
  var form = elm.form;
  form[trg].value = dir ? form[strt].value*obj[einh] : form[strt].value/obj[einh];
}

function selectSizes(el) {
  form = el.form;
  for (var i=0; i<form.elements.length; i++) {
    if (form.elements[i].type=='select-one' && form.elements[i]!=el)
      form.elements[i].selectedIndex = el.selectedIndex;
  }
}