 It should also be mentioned that it is generally assumed that all philosophical and logical aspects of the topic of future contingency can be satisfactory discussed in terms of discrete tense-logic. This means that regarding the topic of future contingency, we may choose to limit the discussion to the discrete case. On the other hand, in some discussions there is no reason to make a limitation of this kind. Prior based the metric version of his general tense-logical system on the operators: 