An idiom referring to a maneuver / method or series of maneuvers and/or methods that can be equally effective for more than one scenario.

Comments:

Basically, Master Key refers to any maneuver / method / series that is interchangeable into a number of different situations while remaining equally effective in each.

The most common references to Master Key are:

Basic (single maneuver / method)

Move (single maneuver / method)

Self-Defense Technique (multiple maneuvers / methods)

This term is closely related to the term Standard Extension in terms of interchangeability.

Example(s):

An inward vertical forearm would demonstrate a Master Key Basic / Move due to its ability to be used both defensively (as a block) and offensively (as a strike).

Delayed Sword would demonstrate a Master Key Technique due to its ability to be used against a number of offensive maneuvers from the attacker (i.e. [attempted] grab, push, roundhouse punch, straight punch).

Related Definition(s):

Block, Formulate, Strike, Weapon

Related Term(s):

Combat Effectiveness, Position Recognition, Standard Extension, Strategic Recognition