function selectCheckboxes(select_state, action_url)
{
  formId = document.getElementById('facilityoptions');
  
  for (var n=0; n < formId.length; n++)
  {
    if (formId.elements[n].type=="checkbox") 
    {
      formId.elements[n].checked=select_state; 
    }
  }

  new Ajax.Updater('geokaart', action_url, {parameters: $('facilityoptions').serialize() }); 
  return true;
}