function validateISearchInput() {
      var elemProducer;
      var elemPrinter;
      var errs = 0;
      
      elemProducer  = document.getElementById("producer");
      elemPrinter  = document.getElementById("printer");
      
      var id1;
      id1 = elemProducer.options[elemProducer.selectedIndex]
      if (id1.value == -1) errs += 1;
      
      var id2;
      id2 = elemPrinter.options[elemPrinter.selectedIndex]
      if (id2.value == -1) errs += 1;      

      if (errs >= 1)  alert('Zvolte prosím výrobce a typ zařízení.');

      return (errs == 0);      

}


function validateFulltextInput() {
      var elemInput;
      var errs = 0;
      
      elemInput  = document.getElementById("fulltext_input_id");
      if (elemInput.value == "") errs += 1;    
      
      return (errs == 0);      

}