Patent ID: 8146391

Claim:
A lock, comprising: a body; a shackle having a toe and a heel, the heel being retained by the body and able to rotate within the body; a first and a second locking mechanism to lock the shackle, each of the locking mechanisms being enabled to independently unlock the shackle, wherein the toe, in an unlocked position of the second locking mechanism, is positioned outside of the body and the toe, in a locked position of the second locking mechanism, is positioned inside the body wherein the toe is surrounded by two opposing walls of the body; a retaining structure comprising a blocking element and a passage, the retaining structure being movable between a first position and a second position by the first locking mechanism; and wherein when the second locking mechanism is in the locked position, when the shackle is aligned with the body and when the retaining structure is in the first position, rotational movement of the toe is restricted; and wherein when the second locking mechanism is in the locked position, when the shackle is aligned with the body, and when the retaining structure is in the second position, the toe is free to move through the passage and the shackle is free to rotate about the heel.