var n4 = 8;
var f4 = false;
var b4 = new Array;

function prel_c(){
	if(document.images) {
		for(i=1;i<=catblocks.length;i++) {
			str = catblocks[i];
			b4[i-1] = new Image();
			b4[i-1].src = str;
		}
		f4 = true;
 	}
}
function on_c(im, src) {
	if (document.images && (f4 == true)) {
		document.images[im].src = src;
	}	
}
function off_c(im, src){
	if (document.images && (f4 == true)) {
		document.images[im].src = src;
	}
}