Every distinct wording since 2010, newest first.
April 23, 2010 · Rise of the Eldrazi
Each object in a pile is still an individual object. The pile is not an object.
February 1, 2010 · Worldwake
Objects grouped into piles don't leave the zone they're currently in. If cards in a graveyard are split into piles, the order of the graveyard must be maintained.