6.2.2030
PICK
 
CORE EXT
 
( xu...x1 x0 u -- xu...x1 x0 xu )

Remove u. Copy the xu to the top of the stack. An ambiguous condition exists if there are less than u+2 items on the stack before PICK is executed.

See:
A.6.2.2030 PICK.

Rationale:
0 PICK is equivalent to DUP and 1 PICK is equivalent to OVER.