var img1 = new Image();
img1.src = "http://www.dbsptech.com/documentation/plus.gif";
var img2 = new Image();
img2.src = "http://www.dbsptech.com/documentation/minus.gif";

function ShowHide (exElement, imgElement) {
  
     if (exElement.style.display == "")
     {
        exElement.style.display = "none";
	    imgElement.src = img1.src;
     }
     else
     {
	   exElement.style.display = "";
	   imgElement.src = img2.src;
     }

}