includes a threaded member 36 u2032 in lieu of leg 36 which is preferably snugly fit into plate 34 of actuator 30 second plate 34 u2032 includes a threaded aperture to receive threaded member 36 u2032 such that threaded member 36 u2032 may be adjusted to selectively determine the function key retaining or non key retaining specified by actuator 30 u2032 in particular with threaded member 36 u2032 adjusted to a retracted position in which no part of the threaded member extends into anchoring recess 28 lost motion may occur and a non key retaining function is specified with threaded member 36 u2032 adjusted to an extended position wherein at least a portion of member 36 u2032 extends into and is trapped by anchoring recess 28 a key retaining function is specified naturally as with the embodiment of fig3 a the desired lock function can be repeatedly selected and unselected without adding or taking away lock components fig3 c shows a reversible tenon pin 36 u2033 for use in a function determinative actuator in accordance with yet another preferred embodiment of the present invention in particular an actuator utilizing reversible tenon pin 36 u2033 is substantially similar to and operates in the same general manner as actuator 30 u2032 there are a number of differences between these actuators first reversible tenon pin 36 u2033 is generally designed to substitute for threaded member 36 u2032 in actuator 30 u2032 pin 36 u2033 preferably includes a threaded first end 39 at one end thereof and an opposite end 39 u2032 having both a threaded region.