Description: probability for an item to be in a state to perform as required at a given instant; Name: immediate Availability
Description: Probability that an item is in a state to perform as required at a given instant, under given conditions, assuming that the necessary external resources are provided ; Name: Instantaneous availability
Description: variable quantity, which is not influenced by the control but is introduced into the control system from outside with the aim of making the final controlled variable follow it in a given relationship; Name: command variable