function textCounter(fieldname, countfieldname, maxlimit) {
field      = document.getElementById(fieldname);
countfield = document.getElementById(countfieldname);

if (field.value.length > maxlimit) // if too long...trim it!
field.value = field.value.substring(0, maxlimit);
// otherwise, update 'characters left' counter
else 
countfield.value = maxlimit - field.value.length;
}

function ShowDatumsfelder() {
         if (document.formular.AB_SOFORT_B[1].checked)
         {
            document.formular.STELLENANTRITT.disabled = false;
            STELLENANTRITT.style.visibility="visible";
         }
          else
         {
          document.formular.STELLENANTRITT.value  = "";
          STELLENANTRITT.style.visibility="hidden";
          document.formular.STELLENANTRITT.disabled = true;
          }
         if (document.formular.UNBEFRISTET_B[1].checked)
         {
            document.formular.VERTRAGSDAUER.disabled = false;
            VERTRAGSDAUER.style.visibility="visible";
         }
          else
         {
          document.formular.VERTRAGSDAUER.value  = "";

          document.formular.VERTRAGSDAUER.disabled = true;
          VERTRAGSDAUER.style.visibility="hidden";
          }

}

function ShowTXTfelder() {
         if (document.formular.TELETEXT[2].checked)
         {
          TELETEXT.style.visibility="hidden";
          document.formular.TELETEXT_KANAL_CODE.disabled = true;
          document.formular.TELETEXT_ZUSATZTEXT.disabled = true;
         }
          else
         {
            document.formular.TELETEXT_KANAL_CODE.disabled = false;
            document.formular.TELETEXT_ZUSATZTEXT.disabled = false;
            TELETEXT.style.visibility="visible";
          }

}