function togglefields() {
  var f = document.addbuilding;
  var d = f.elements['descr'];
  var bdt = f.elements['bdtype'];

  var allfields = new Array('accomondate',
                            'military_accom',
                            'poweroutput',
                            'buildoutput',
                            'researchoutput',
                            'storage');
  var enablefields = new Array();

  for (i=0; i<allfields.length; i++) f.elements[allfields[i]].disabled=true;

  switch (bdt.options[bdt.selectedIndex].value) {
  case 'barrack':
    enablefields.push('military_accom');
    break;
  case 'buildingplant':
    enablefields.push('buildoutput');
    break;
  case 'colonycenter':
    enablefields.push('accomondate');
    enablefields.push('buildoutput');
    enablefields.push('poweroutput');
    enablefields.push('storage');
    break;
  case 'house':
    enablefields.push('accomondate');
    break;
  case 'powerplant':
    enablefields.push('poweroutput');
    break;
  case 'researchcenter':
    enablefields.push('researchoutput');
    break;
  case 'warehouse':
    enablefields.push('storage');
    break;
  case '':
    enablefields.push('');
    break;
  }

  for (i=0; i<enablefields.length; i++) f.elements[enablefields[i]].disabled=false;
}