When clubs consent to include a player to be named later (often abbreviated PTBNL) in a trade, they agree to decide upon or announce the final player involved in that trade at a later date.
Using a PTBNL can be especially advantageous after the non-waiver Trade Deadline, as players that would otherwise be required to first clear waivers can be included in the trade as a PTBNL -- provided they are not on the 25-man roster -- and officially sent to their new club once waiver clearance is no longer mandatory for a trade.
In other instances, the club sending the PTBNL away will provide the acquiring club with a list of players from which to select the PTBNL. In such cases, an agreed-upon deadline -- by which the acquiring club must select the PTBNL -- will often be set.
The July 2007 trade that sent CC Sabathia from the Indians to the Brewers saw Cleveland receive first baseman Matt LaPorta, left-hander Zach Jackson, right-hander Rob Bryson and a PTBNL. The deal was supposed to be centered around LaPorta, but the PTBNL -- Michael Brantley -- has made a far greater big league impact than anyone else the Indians acquired in the transaction.