if (document.images) {
		//two example categories have been added below - tag your own onto the bottom for each category: 
		
		//av-konferenz category - begin
		nav21 = new Image; nav21.src="images/navigation/nav21.png";
		nav21_over = new Image; nav21_over.src="images/navigation/nav21_over.png";
			
		nav21_30 = new Image; nav21_30.src="images/navigation/nav21_30.png";
		nav21_30_over = new Image; nav21_30_over.src="images/navigation/nav21_30_over.png";
		
			
		//add more categories here:
		// ...
		
	}
		
	function chgImg(imgField,newImg)	{
		if (document.images)	{
			document[imgField].src= eval(newImg + ".src")
		}
	}