function clearIt( box ) {
  if(box.value==box.defaultValue) {
	  box.value = "";
	}
}

function updateForm( form,pagina ) {
  var stijlID = form.stijlID.options[form.stijlID.options.selectedIndex].value;
  var soort = form.soort.options[form.soort.options.selectedIndex].value;
  var instrumentID = form.instrumentID.options[form.instrumentID.options.selectedIndex].value;
  self.location = '?stijlID=' + stijlID + '&soort=' + soort + '&instrumentID=' + instrumentID;
}

function checkStijl(form) {
  var stijlValue = form.stijl.options[form.stijl.options.selectedIndex].value;
  if (stijlValue=='anders') {
    form.stijl_optie[0].checked = false;
    form.stijl_optie[0].disabled = true;
    form.stijl_optie[1].checked = true;
    document.getElementById('nwestijl').style.display = 'block';
  } else {
    form.stijl_optie[0].checked = true;
    form.stijl_optie[0].disabled = false;
    form.stijl_optie[1].checked = false;
    document.getElementById('nwestijl').style.display = 'none';
  }
}

function checkInstrument(form) {
  var InstrumentValue = form.instrument.options[form.instrument.options.selectedIndex].value;
  if (InstrumentValue=='anders') {
    form.instrument_optie[0].checked = false;
    form.instrument_optie[0].disabled = true;
    form.instrument_optie[1].checked = true;
    document.getElementById('nweinstrument').style.display = 'block';
  } else {
    form.instrument_optie[0].checked = true;
    form.instrument_optie[0].disabled = false;
    form.instrument_optie[1].checked = false;
    document.getElementById('nweinstrument').style.display = 'none';
  }
}