from latest avesta revision:
function onUse(cid, item, frompos, item2, topos)
if(topos.x == 0 and topos.y == 0 and topos.z == 0) then
doPlayerSendDefaultCancel(cid, RETURNVALUE_NOTPOSSIBLE)
return FALSE
end
topos.stackpos = 255
local tmp = getThingfromPos(topos)
if (tmp.itemid ~=...