function PVoverImage(iname) { 
    if (document.images) { 
        var src = document.images[iname].src; 
        var off = src.lastIndexOf("of.gif"); 
        if (off != -1) { 
            document.images[iname].src = src.substring(0,off) + "on" + ".gif"; 
        } 
    } 
} 
function PVoffImage(iname) { 
    if (document.images) { 
        var src = document.images[iname].src; 
        var on = src.lastIndexOf("on.gif"); 
        if (on != -1) { 
            document.images[iname].src = src.substring(0,on) + "of" + ".gif"; 
        } 
    } 
}