function savePlayerData (player,datatype,newvalue)
  local playerIP = getPlayerSerial (player)
  if (playerIP) then
    local root = xmlLoadFile ("users.xml")
    if (root) then
      local usersNode = xmlFindChild (root,"user",0)
      if (usersNode) then
        local playerRootNode = xmlFindChild (usersNode,"SERIAL_" .. getPlayerSerial(player),0)
        if not (playerRootNode == false) then
          local newNodeValue = xmlNodeSetAttribute (playerRootNode,datatype,newvalue)
          xmlSaveFile (root)
          xmlUnloadFile (root)
          return newNodeValue
        else
          local playerRootNode = xmlCreateChild (usersNode,"SERIAL_" .. getPlayerSerial(player))
          local newNodeValue = xmlNodeSetAttribute (playerRootNode,datatype,newvalue)
          xmlSaveFile (root)
          xmlUnloadFile (root)
          return newNodeValue
        end
      end
    end
  end
end