function ceers_check() {
  if (element("row_prijmeni").style.display != "none" && !element("prijmeni").value) {
    alert("The field 'Family Name' is mandatory. Please, fill this field.");
    element("prijmeni").focus();
    return false;
  }

  if (element("row_jmeno").style.display != "none" && !element("jmeno").value) {
    alert("The field 'First Name' is mandatory. Please, fill this field.");
    element("jmeno").focus();
    return false;
  }

  if (element("row_firma").style.display != "none" && !element("firma").value) {
    alert("The field 'Company' is mandatory. Please, fill this field.");
    element("firma").focus();
    return false;
  }

  if (element("row_adresa").style.display != "none" && !element("adresa").value) {
    alert("The field 'Address' is mandatory. Please, fill this field.");
    element("adresa").focus();
    return false;
  }

  if (element("row_psc").style.display != "none" && !element("psc").value) {
    alert("The field 'Postal/ZIP-Code' is mandatory. Please, fill this field.");
    element("psc").focus();
    return false;
  }

  if (element("row_mesto").style.display != "none" && !element("mesto").value) {
    alert("The field 'City' is mandatory. Please, fill this field.");
    element("mesto").focus();
    return false;
  }

  if (element("row_stat").style.display != "none" && !element("stat").value) {
    alert("The field 'Country' is mandatory. Please, fill this field.");
    element("stat").focus();
    return false;
  }

  if (element("row_email").style.display != "none" && !element("email").value) {
    alert("The field 'E-mail' is mandatory. Please, fill this field.");
    element("email").focus();
    return false;
  }

  if (!element("vecere").selectedIndex == 0) {
    alert("The field 'The dinner on October 14, 2009' is mandatory. Please, fill this field.");
    element("vecere").focus();
    return false;
  }

  return true;
}

function ceers_prereg() {
var persons = new Array();
persons['Aigner-Breuss Eva'] = 'AT / Austrian Road Safety Board (KfV)';
persons['Antolović Dražen'] = 'HR / Ministry of Sea, Transport and Infrastructure';
persons['Ambros Jiří'] = 'CZ / Transport Research Centre (CDV)';
persons['Ambrožová Zuzana'] = 'CZ / Ministry of Transport';
persons['Bezák Bystrík'] = 'SK / Slovak University of Technology in Bratislava';  
persons['Bolanča Vjekoslav'] = 'HR / Ministry of Sea, Transport and Infrastructure';  
persons['Breyer Günther'] = 'AT / Federal Ministry for Transport, Innovation and Technology';  
persons['Buttler Ilona'] = 'PL / Motor Transport Institute (ITS)';  
persons['Dujso Mehmed'] = 'BA / Ministry of Communications and Transport';  
persons['Dohnal Ivan'] = 'SK / Slovak Road Administration, Road Traffic Safety Centre';
persons['Dont Milan'] = 'CZ / Transport Research Centre (CDV)';  
persons['Diaconu Iustina'] = 'RO / Global Road Safety Partnership Program';  
persons['Dont Milan'] = 'CZ / Transport Research Centre (CDV)';  
persons['Eichinger-Vill Eva'] = 'AT / Federal Ministry for Transport, Innovation and Technology';  
persons['Erenli Eva'] = 'AT / Austrian Road Safety Board (KfV)';  
persons['Fertner Maria-Luise'] = 'AT / Austrian Road Safety Board (KfV)';  
persons['Feßl Thomas'] = 'AT / Austrian Road Safety Board (KfV)';  
persons['Frič Jindřich'] = 'CZ / Transport Research Centre (CDV)';  
persons['Fürdös Alexander'] = 'AT / Austrian Road Safety Board (KfV)';  
persons['Gönczi Attila'] = 'RO / Politehnica University of Timisoara';  
persons['Grzegorczyk Andrzej'] = 'PL / Ministry of Infrastructure';  
persons['Hadzic Demir'] = 'RS / Ministry of Infrastructure, Road Safety Department';  
persons['Hodzić Mensur'] = 'BA / Ministry of Communications and Transport';  
persons['Holló Péter'] = 'HU / Institute for Transport Sciences (KTI)';  
persons['Kluza Katarzyna'] = 'PL / Ministry of Infrastructure';
persons['Lányi Péter'] = 'HU / Ministry of Transport, Telecommunication and Energy';  
persons['Król Barbara'] = 'PL / Ministry of Infrastructure';  
persons['Lisá Zuzana'] = 'CZ / Ministry of Transport';  
persons['Maatz Andreas'] = 'AT / Austrian Road Safety Board (KfV)';  
persons['Machata Klaus'] = 'AT / Austrian Road Safety Board (KfV)';  
persons['Machciník Štefan'] = 'SK / Transport Research Institute (VUD)';  
persons['Malasek Jacek'] = 'PL / Road and Bridge Research Institute (IBDIM)';  
persons['Markl Mateja'] = 'SI / Ministry of Transport, Slovenian Roads Agency';  
persons['Meindl Alexandra'] = 'AT / Austrian Road Safety Board (KfV)';  
persons['Meliška Karol'] = 'SK / Ministry of Transport, Post and Telecommunications';  
persons['Mikulík Josef'] = 'CZ / Transport Research Centre (CDV)';  
persons['Nikolić Nenad'] = 'RS / South-East Europe Transport Observatory (SEETO)';  
persons['Nussbaumer Cornelia'] = 'AT / Austrian Road Safety Board (KfV)';  
persons['Osrael Ernestine'] = 'AT / Austrian Road Safety Board (KfV)';  
persons['Pantchev Valentin'] = 'BU / Ministry of Transport and Communications';  
persons['Pavčič Tomaž'] = 'SI / Ministry of Transport, Slovenian Roads Agency';  
persons['Pokorný Petr'] = 'CZ / Transport Research Centre (CDV)';  
persons['Pristaš Štefan'] = 'SK / Ministry of Transport, Post and Telecommunications';  
persons['Robatsch Klaus'] = 'AT / Austrian Road Safety Board (KfV)';  
persons['Schausberger Bernhard'] = 'AT / Cross-Border Program Slovakia-Austria 2007-2013';  
persons['Stefan Christian'] = 'AT / Austrian Road Safety Board (KfV)';  
persons['Strnad Bernd'] = 'AT / Austrian Road Safety Board (KfV)';  
persons['Strnadová Zuzana'] = 'CZ / Transport Research Centre (CDV)';  
persons['Tučka Pavel'] = 'CZ / Transport Research Centre (CDV)';  
persons['Vujanic Milan'] = 'RS / University of Belgrade, Faculty of Traffic and Transport';  
persons['Zaoral Aleš'] = 'CZ / Transport Research Centre (CDV)';  
persons['Zlender Bojan'] = 'SI / Ministry of Transport, Slovenian Roads Agency';  

var osoba = element("prereg_jmeno").value;
var stat = element("prereg_stat_firma").value;

if (osoba && stat) {
  var rows = new Array("row_noprereg", "row_pohlavi", "row_prijmeni", "row_jmeno", "row_titul", "row_firma", "row_funkce", "row_adresa", "row_psc", "row_mesto", "row_stat", "row_telefon", "row_fax");

  var class = (persons[osoba] == stat ? "none" : "table-row");

  for (var i=0;i<rows.length;i++) {
    if (element(rows[i])) {
     element(rows[i]).style.display = class;
    }
  }

  if (persons[osoba] != stat) {
    alert("Unfotunately, this combination of name and company is not valid.");
    element("prereg_stat_firma").selectedIndex = 0;
  }
 }
}