This activator is linked to defined item and executing while player holding it in hand (every 3 seconds).
To create use command:
/react add ITEM_HOLD <ActivatorId>
|%item%||Text representation of item that was in player hands, that could be use to "create" another items using actions ITEM_GIVE, ITEM_DROP, etc.|
|%item-str%||Description of item, that will composed from item's name, data and amount.|