function valideer(formulier) {
 var missing = "";
 var regexp= /^[A-Z]/;
 var i;
 var pnam="";
 var completed=true;
 for(i=0; i < formulier.elements.length; i++) {
  with(formulier.elements[i]){
   if(pnam != name ) {
    if(!completed) {
     missing += "\t" + pnam + "\n";
    }
    pnam=name;
    completed=false;
   }
   if(regexp.test(name)) {
    if(type == "hidden") {
     completed=true;
    } else {
     if((type == "text") || (type=="select-one")) {
      if(value != "") {
       completed=true;
      }
     } else if(type == "radio") {
      if(checked) {
       completed=true;
      }
     }
     if(missing == "") {
      focus();
     }
    }
   } else {
    completed=true;
   }
  }
 }
 if(!completed) {
  missing += "\t" + pnam + "\n";
 }
 if (missing == "") {
  return true;
 } else {
  alert("De volgende gegevens zijn ten onrechte niet ingevuld:\n\n" + missing);
  return false;
 }
}