function updateRegion() {
    var mainRegionSelect = document.forms.Unterkunftsdaten.hauptregion;
    var regionSelect = document.forms["Unterkunftsdaten"].elements["region[]"];
    regionSelect.length = 0; // DropDown Menü entleeren
    regionSelect.style.visibility="hidden";
    if (mainRegionSelect.options[mainRegionSelect.selectedIndex].value=="D_BW") {
      regionSelect.style.visibility="visible";
      var regionName=new Array ("","Allgäu","Baden","Bodensee","Breisgau","Hochrhein","Hohenlohe","Kaiserstuhl","Kraichgau","Kurpfalz","Neckartal","Odenwald","Ortenau","Region Stuttgart","Rhein-Neckar-Gebiet","Schwaben","Schwäbische Alb","Schwäbischer Wald","Schwarzwald","Taubertal","Württemberg");
      var regionWert=new Array ("","Allgaeu","Baden","Bodensee","Breisgau","Hochrhein","Hohenlohe","Kaiserstuhl","Kraichgau","Kurpfalz","Neckartal","Odenwald","Ortenau","Region_Stuttgart","Rhein-Neckar-Gebiet","Schwaben","Schwaebische_Alb","Schwaebischer_Wald","Schwarzwald","Taubertal","Wuerttemberg");
	}    
    
    if (mainRegionSelect.options[mainRegionSelect.selectedIndex].value=="D_BY") {
      regionSelect.style.visibility="visible";
      var regionName=new Array ("","Allgäu","Altmühltal","Arber-Region","Bayerischer Wald","Berchtesgadener Land","Bodensee","Chiemgau","Fichtelgebirge","Fränkische Schweiz","Franken","Frankenwald","Großraum München","Oberbayern","Oberpfalz","Ostbayern","Rhön","Schwaben","Schwäbische Alb","Spessart","Taubertal","Voralpenland","Zugspitzland");
      var regionWert=new Array ("","Allgaeu","Altmuehltal","Arber-Region","Bayerischer_Wald","Berchtesgadener_Land","Bodensee","Chiemgau","Fichtelgebirge","Fraenkische_Schweiz","Franken","Frankenwald","Grossraum_Muenchen","Oberbayern","Oberpfalz","Ostbayern","Rhoen","Schwaben","Schwaebische_Alb","Spessart","Taubertal","Voralpenland","Zugspitzland");
	}    
    
    if (mainRegionSelect.options[mainRegionSelect.selectedIndex].value=="D_BE") {
      regionSelect.style.visibility="visible";
      var regionName=new Array ("","Berliner Umland","Berlin-Charlottenburg","Berlin-Friedrichshain","Berlin-Hellersdorf","Berlin-Hohenschönhausen","Berlin-Köpenick","Berlin-Kreuzberg","Berlin-Lichtenberg","Berlin-Marzahn","Berlin-Mitte","Berlin-Neukölln","Berlin-Pankow","Berlin-Prenzlauer Berg","Berlin-Reinickendorf","Berlin-Schöneberg","Berlin-Spandau","Berlin-Steglitz","Berlin-Tempelhof","Berlin-Tiergarten","Berlin-Treptow","Berlin-Wedding","Berlin-Weißensee","Berlin-Wilmersdorf","Berlin-Zehlendorf");
      var regionWert=new Array ("","Berliner_Umland","Berlin-Charlottenburg","Berlin-Friedrichshain","Berlin-Hellersdorf","Berlin-Hohenschoenhausen","Berlin-Koepenick","Berlin-Kreuzberg","Berlin-Lichtenberg","Berlin-Marzahn","Berlin-Mitte","Berlin-Neukoelln","Berlin-Pankow","Berlin-Prenzlauer_Berg","Berlin-Reinickendorf","Berlin-Schoeneberg","Berlin-Spandau","Berlin-Steglitz","Berlin-Tempelhof","Berlin-Tiergarten","Berlin-Treptow","Berlin-Wedding","Berlin-Weissensee","Berlin-Wilmersdorf","Berlin-Zehlendorf");
	}    
    
    if (mainRegionSelect.options[mainRegionSelect.selectedIndex].value=="D_BG") {
      regionSelect.style.visibility="visible";
      var regionName=new Array ("","Barnim","Berliner Umland","Elbe-Elster-Land","Havelland","Lausitz","Märkisch Oderland","Niederlausitz","Oberhavel","Oder-Spree-Seengebiet","Potsdam-Mittelmark","Prignitz","Ruppiner Land","Spreewald","Spree-Neiße","Teltow-Fläming","Uckermark");
      var regionWert=new Array ("","Barnim","Berliner_Umland","Elbe-Elster-Land","Havelland","Lausitz","Maerkisch-Oderland","Niederlausitz","Oberhavel","Oder-Spree-Seengebiet","Potsdam-Mittelmark","Prignitz","Ruppiner_Land","Spreewald","Spree-Neisse","Teltow-Flaeming","Uckermark");
	}    
    
    if (mainRegionSelect.options[mainRegionSelect.selectedIndex].value=="D_BR") {
      regionSelect.style.visibility="visible";
      var regionName=new Array ("","Bremen","Bremerhaven");
      var regionWert=new Array ("","Bremen","Bremerhaven");
	}    
    
    if (mainRegionSelect.options[mainRegionSelect.selectedIndex].value=="D_HH") {
      regionSelect.style.visibility="visible";
      var regionName=new Array ("","Altona","Bergedorf","Eimsbüttel","Hamburger Umland","Hamburg-Mitte","Hamburg-Nord","Harburg","Wandsbek");
      var regionWert=new Array ("","Altona","Bergedorf","Eimsbuettel","Hamburger_Umland","Hamburg-Mitte","Hamburg-Nord","Harburg","Wandsbek");
	}    
    
    if (mainRegionSelect.options[mainRegionSelect.selectedIndex].value=="D_HE") {
      regionSelect.style.visibility="visible";
      var regionName=new Array ("","Edersee","Großraum Frankfurt","Hessisches Bergland","Lahn-Dill","Nordhessen","Odenwald","Rhein-Lahn-Taunus","Rhein-Main-Gebiet","Rheingau","Rhön","Rothaarsteig","Sauerland","Spessart","Taunus","Waldecker Land","Waldhessen","Werra-Meißner-Land","Weserbergland","Westerwald","Wetterau","Vogelsberg");
      var regionWert=new Array ("","Edersee","Grossraum_Frankfurt","Hessisches_Bergland","Lahn-Dill","Nordhessen","Odenwald","Rhein-Lahn-Taunus","Rhein-Main-Gebiet","Rheingau","Rhoen","Rothaarsteig","Sauerland","Spessart","Taunus","Waldecker_Land","Waldhessen","Werra-Meissner-Land","Weserbergland","Westerwald","Wetterau","Vogelsberg");
	}    
    
    if (mainRegionSelect.options[mainRegionSelect.selectedIndex].value=="D_MV") {
      regionSelect.style.visibility="visible";
      var regionName=new Array ("","Rügen","Ostseeküste","Mecklenburgische Seenplatte","Usedom","Fischland Darß-Zingst","Vorpommern","Hiddensee","Müritz","Mecklenburgische Schweiz","Mecklenburg-Schwerin");
      var regionWert=new Array ("","Ruegen","Ostseekueste","Mecklenburgische_Seenplatte","Usedom","Fischland_Darss-Zingst","Vorpommern","Hiddensee","Mueritz","Mecklenburgische_Schweiz","Mecklenburg-Schwerin");
	}    
    
    if (mainRegionSelect.options[mainRegionSelect.selectedIndex].value=="D_NI") {
      regionSelect.style.visibility="visible";
      var regionName=new Array ("","Borkum","Braunschweiger Land","Elbe-Weser","Emsland","Grafschaft Bentheim","Hannover Region","Harz","Juist","Lübecker Bucht","Lüneburger Heide","Mittelweser","Nordseeküste","Oldenburger Münsterland","Osnabruecker Land","Ostfriesische Inseln","Ostfriesland","Wendland","Weserbergland");
      var regionWert=new Array ("","Borkum","Braunschweiger_Land","Elbe-Weser","Emsland","Grafschaft_Bentheim","Hannover-Region","Harz","Juist","Luebecker_Bucht","Lueneburger_Heide","Mittelweser","Nordseekueste","Oldenburger_Muensterland","Osnabruecker_Land","Ostfriesische_Inseln","Ostfriesland","Wendland","Weserbergland");
	}    
    
    if (mainRegionSelect.options[mainRegionSelect.selectedIndex].value=="D_NO") {
      regionSelect.style.visibility="visible";
      var regionName=new Array ("","Bergisches Land","Eifel","Mittelrhein","Münsterland","Niederrhein","Ostwestfalen-Lippe","Rheinland","Ruhrgebiet","Sauerland","Siegerland","Südwestfalen","Teutoburger Wald","Weserbergland");
      var regionWert=new Array ("","Bergisches_Land","Eifel","Mittelrhein","Muensterland","Niederrhein","Ostwestfalen-Lippe","Rheinland","Ruhrgebiet","Sauerland","Siegerland","Suedwestfalen","Teutoburger_Wald","Weserbergland");
	}    
    
    if (mainRegionSelect.options[mainRegionSelect.selectedIndex].value=="D_RP") {
      regionSelect.style.visibility="visible";
      var regionName=new Array ("","Ahrtal","Eifel","Hunsrück-Nahe","Mittelrhein","Mosel-Saar","Pfalz","Pfälzer Wald","Region Trier","Rhein-Lahn-Taunus","Rheinhessen","Westerwald");
      var regionWert=new Array ("","Ahrtal","Eifel","Hunsrueck-Nahe","Mittelrhein","Mosel-Saar","Pfalz","Pfaelzer_Wald","Region_Trier","Rhein-Lahn-Taunus","Rheinhessen","Westerwald");
	}    
    
    if (mainRegionSelect.options[mainRegionSelect.selectedIndex].value=="D_SL") {
      regionSelect.style.visibility="visible";
      var regionName=new Array ("","Merzig-Wadern","Neunkirchen","Saarbrücken","Saarlouis","Saarpfalz","Saartal","Sankt Wendel");
      var regionWert=new Array ("","Merzig-Wadern","Neunkirchen","Saarbruecken","Saarlouis","Saarpfalz","Saartal","Sankt_Wendel");
	}    
    
    if (mainRegionSelect.options[mainRegionSelect.selectedIndex].value=="D_SN") {
      regionSelect.style.visibility="visible";
      var regionName=new Array ("","Burgen- und Heideland","Dresden","Erzgebirge","Lausitz","Leipzig","Niederschlesien","Oberlausitz","Sächsische Schweiz","Sächsisches Elbland","Vogtland","Westsachsen");
      var regionWert=new Array ("","Burgen-und_Heideland","Dresden","Erzgebirge","Lausitz","Leipzig","Niederschlesien","Oberlausitz","Saechsische_Schweiz","Saechsisches_Elbland","Vogtland","Westsachsen");
	}    
    
    if (mainRegionSelect.options[mainRegionSelect.selectedIndex].value=="D_SA") {
      regionSelect.style.visibility="visible";
      var regionName=new Array ("","Altmark","Anhalt-Wittenberg","Bodetal","Brocken","Elbe-Börde-Heide","Harz","Saale-Unstrut");
      var regionWert=new Array ("","Altmark","Anhalt-Wittenberg","Bodetal","Brocken","Elbe-Boerde-Heide","Harz","Saale-Unstrut");
	}    
    
    if (mainRegionSelect.options[mainRegionSelect.selectedIndex].value=="D_SH") {
      regionSelect.style.visibility="visible";
      var regionName=new Array ("","Amrum","Dithmarschen","Eiderstedt","Fehmarn","Föhr","Grünes Binnenland","Halligen","Holsteinische Schweiz","Lübecker Bucht","Lüneburger Heide","Ostseeküste","Nordfriesland","Nordseeküste","Probstei","Sylt","Timmendorfer Strand");
      var regionWert=new Array ("","Amrum","Dithmarschen","Eiderstedt","Fehmarn","Foehr","Gruenes_Binnenland","Halligen","Holsteinische_Schweiz","Luebecker_Bucht","Lueneburger_Heide","Ostseekueste","Nordfriesland","Nordseekueste","Probstei","Sylt","Timmendorfer_Strand");
	}    
    
    if (mainRegionSelect.options[mainRegionSelect.selectedIndex].value=="D_TH") {
      regionSelect.style.visibility="visible";
      var regionName=new Array ("","Kyffhäuser","Harz","Nordthüringen","Ostthüringen","Rennsteig","Rhön","Saaleland","Thüringer Kernland","Thüringer Wald","Weimarer Land");
      var regionWert=new Array ("","Kyffhaeuser","Harz","Nordthueringen","Ostthueringen","Rennsteig","Rhoen","Saaleland","Thueringer_Kernland","Thueringer_Wald","Weimarer_Land");
	}    
    
    if (mainRegionSelect.options[mainRegionSelect.selectedIndex].value=="A_BL") {
      regionSelect.style.visibility="visible";
      var regionName=new Array ("","Mittelburgenland","Neusiedler See","Nördliches Burgenland","Sonnenland","Südburgenland");
      var regionWert=new Array ("","Mittelburgenland","Neusiedler_See","Noerdliches_Burgenland","Sonnenland","Suedburgenland");
	}    
    
    if (mainRegionSelect.options[mainRegionSelect.selectedIndex].value=="A_KT") {
      regionSelect.style.visibility="visible";
      var regionName=new Array ("","Hohe Tauern - Großglockner","Lavanttal","Lieser-Maltatal","Millstädter See","Mittelkärnten","Nockberge","Region Klagenfurt","Region Villach","Turracher Höhe","Südkärnten","Wörthersee");
      var regionWert=new Array ("","Hohe_Tauern-Grossglockner","Lavanttal","Lieser-Maltatal","Millstaedter_See","Mittelkaernten","Nockberge","Region_Klagenfurt","Region_Villach","Turracher_Hoehe","Suedkaernten","Woerthersee");
	}    
    
    if (mainRegionSelect.options[mainRegionSelect.selectedIndex].value=="A_NI") {
      regionSelect.style.visibility="visible";
      var regionName=new Array ("","Mostviertel","Region Donau","Schneebergland","Waldviertel");
      var regionWert=new Array ("","Mostviertel","Region_Donau","Schneebergland","Waldviertel");
	}    
    
    if (mainRegionSelect.options[mainRegionSelect.selectedIndex].value=="A_OB") {
      regionSelect.style.visibility="visible";
      var regionName=new Array ("","Abersee","Ferienregion Attersee","Hausruckviertel","Linz und Umgebung","Mühlviertel","Salzkammergut");
      var regionWert=new Array ("","Abersee","Ferienregion_Attersee","Hausruckviertel","Linz_und_Umgebung","Muehlviertel","Salzkammergut");
	}    
    
    if (mainRegionSelect.options[mainRegionSelect.selectedIndex].value=="A_SA") {
      regionSelect.style.visibility="visible";
      var regionName=new Array ("","Abersee","Gastein","Großarltal","Hochkönig","Lammertal","Nationalpark Hohe Tauern","Obertauern","Raurisertal","Saalbach-Hinterglemm","Salzburger Sportwelt","Salzkammergut","Tennengebirge","Zell am See – Kaprun");
      var regionWert=new Array ("","Abersee","Gastein","Grossarltal","Hochkoenig","Lammertal","Nationalpark_Hohe_Tauern","Obertauern","Raurisertal","Saalbach-Hinterglemm","Salzburger_Sportwelt","Salzkammergut","Tennengebirge","Zell_am_See_–_Kaprun");
	}    
    
    if (mainRegionSelect.options[mainRegionSelect.selectedIndex].value=="A_ST") {
      regionSelect.style.visibility="visible";
      var regionName=new Array ("","Almenland","Dachstein","Graz und Umgebung","Hochsteiermark","Murtal","Nationalpark Gesäuse","Oststeiermark","Stanzertal","Steirisches Thermenland","Weststeiermark");
      var regionWert=new Array ("","Almenland","Dachstein","Graz_und_Umgebung","Hochsteiermark","Murtal","Nationalpark_Gesaeuse","Oststeiermark","Stanzertal","Steirisches_Thermenland","Weststeiermark");
	}    
    
    if (mainRegionSelect.options[mainRegionSelect.selectedIndex].value=="A_TI") {
      regionSelect.style.visibility="visible";
      var regionName=new Array ("","Achensee","Alpbachtal","Defereggental","Ferienregion Kufstein","Ferienregion Reutte","Imst/Gurgltal","Kaiserwinkl","Kaunertal","Kitzbühler Alpen","Lechtal","Lienzer Dolomiten","Mayrhofen","Mieminger Plateau","Ötztal","Osttirol","Paznauntal","Pustertal","Region Hall Wattens","Region Innsbruck","Seefeld","Stubaital","Tiroler Oberland","Wilder Kaiser","Zillertal","Zugspitz-Arena");
      var regionWert=new Array ("","Achensee","Alpbachtal","Defereggental","Ferienregion_Kufstein","Ferienregion_Reutte","Imst","Kaiserwinkl","Kaunertal","Kitzbuehler_Alpen","Lechtal","Lienzer_Dolomiten","Mayrhofen","Mieminger_Plateau","Oetztal","Osttirol","Paznauntal","Pustertal","Region_Hall_Wattens","Region_Innsbruck","Seefeld","Stubaital","Tiroler_Oberland","Wilder_Kaiser","Zillertal","Zugspitz-Arena");
	}    
    
    if (mainRegionSelect.options[mainRegionSelect.selectedIndex].value=="A_VO") {
      regionSelect.style.visibility="visible";
      var regionName=new Array ("","Arlberg","Bregenzerwald","Großes Walsertal","Kleinwalsertal","Montafon");
      var regionWert=new Array ("","Arlberg","Bregenzerwald","Grosses_Walsertal","Kleinwalsertal","Montafon");
	}    
    
    if (mainRegionSelect.options[mainRegionSelect.selectedIndex].value=="A_WI") {
      regionSelect.style.visibility="visible";
      var regionName=new Array ("","Wien");
      var regionWert=new Array ("","Wien");
	}    
    	
    for(var i in regionName) {
      regionSelect.options[i] = new Option(regionName[i], regionWert[i]);
    }
  }