// 'lid van de npmb' & 'geboortedatum -plaats' aanzetten als actie is 'cursus downloaden'
function changeActie() {
  if (document.formNPMB.cursus.checked) {
      document.getElementById('geboorte1').style.visibility = 'visible';
      document.getElementById('geboorte2').style.visibility = 'visible';
      if (document.formNPMB.lid.checked) {
          document.getElementById('lidtext').style.visibility = 'hidden';
          document.getElementById('lidveld').style.visibility = 'hidden';
          if (document.formNPMB.allid.checked) {
              document.getElementById('lidtext2').style.visibility = 'hidden';
          } else {
              document.getElementById('lidtext2').style.visibility = 'visible';
          }
      } else {
          document.getElementById('lidtext').style.visibility = 'visible';
          document.getElementById('lidveld').style.visibility = 'visible';
          document.getElementById('lidtext2').style.visibility = 'visible';
      }
  } else {
      document.getElementById('geboorte1').style.visibility = 'hidden';
      document.getElementById('geboorte2').style.visibility = 'hidden';
      document.getElementById('lidtext').style.visibility = 'hidden';
      document.getElementById('lidveld').style.visibility = 'hidden';
      document.getElementById('lidtext2').style.visibility = 'hidden';
  }
}

// 'lidnummer' aanzetten als 'lid' is aangevinkt
function changeAlLid() {
  if (document.formNPMB.allid.checked) {
      document.getElementById('lidtext2').style.visibility = 'hidden';
  } else {
      document.getElementById('lidtext2').style.visibility = 'visible';
  }
}