Abstract: Lock apparatus comprising a housing in which is movably supported a locking member for movement between locked and unlocked positions. The housing and locking member have aligned bores containing blocking pins supported for movement between a first position in which the locking member is movable relative to the housing and a second position in which the blocking pins block movement of the locking member relative to the housing. A plate-like key member and a plate-like code member are respectively insertable into slots provided in the housing. The bores in the housing and locking member are arranged in a predetermined pattern and the plate-like members have respective regions corresponding to the location of the bores in the pattern.