The 2007 Laws define Start and End of Auction, Auction Period, Clarification Period etc. They also define the Start of the Play Period (i.e. when a legal card is faced). However there is no definition of when the Play Period ends. There is a definition of the Round End (Law 8). This definition would clarify for example Law 66D - After Conclusion Of Play, .......(for how long can the played and unplayed cards be inspected etc.)