img_dir="../images/";
function pItem (name, width, height) {
this.on = new Image();
this.on.src =img_dir+"/"+name + "on.gif"
this.off = new Image();
this.off.src =img_dir+"/"+ name + "off.gif"
}
function p_new (name) {
pItem[name] = new pItem(name);
}
function img_act (imgName) {
    if (document.images) document[imgName].src = pItem[imgName].on.src;
}
function img_inact (imgName) {
    if (document.images) document [imgName].src = pItem[imgName].off.src;
}
function load_p (name, num) {
for (i = 1; i <= num; i++) p_new(name + i);
}
    if (document.images != null) load_p ('p', 10);