if (document.layers) {
  reveal = 'block';
  unreveal = 'none';
  visible = 'show';
  hidden = 'hide';
} else if (document.all) {
  reveal = 'block';
  unreveal = 'none';
  visible = 'visible';
  hidden = 'hidden';
}





function ShowDropDown(block) {
	if (document.layers) {
		showDropDown = document.layers[block];		
	} else if (document.all) {	
		showDropDown = document.all(block).style;
	}   
 
	showDropDown.visibility = visible;	 	 
}

function HideDropDown(block) {
	if (document.layers) {
		hideDropDown = document.layers[block];		
	} else if (document.all) {	
		hideDropDown = document.all(block).style;
	}   
 
	hideDropDown.visibility = hidden;	 	 
}

function HideAllDropDowns() {
	if (document.layers) {
                Collection.visibility = hidden;
                Available.visibility = hidden;
                Updates.visibility = hidden;		
		Husbandry.visibility = hidden; 
		Reproduction.visibility = hidden; 
		Articles.visibility = hidden;

	} else if (document.all) {	
		Collection.style.visibility = hidden;
		Available.style.visibility = hidden;
		Updates.style.visibility = hidden;
                Husbandry.style.visibility = hidden; 
		Reproduction.style.visibility = hidden; 
		Articles.style.visibility = hidden;
	}   
		 	 
}