A value of Tense Property assigned to the designated element in the clause when the meaning selected for the clause is that intended to locate the event spoken about as posterior to the deictic centre of the utterance. Most commonly, this tense meaning is referred to as 'future', because in absolute tense systems the deictic centre is the moment of speech. However, in relative tense systems, where the deictic centre can be moved to any point on the time line, it is more appropriate to refer to this temporal relation as 'posterior'.
The posterior temporal relation may obtain either in 'simple' or 'perfect' contexts. Modelling of this distinction originates from [Reichenbach 1947], who suggested using a third point in time, 'reference point', to capture all possible tense distinctions. In all 'simple' temporal relations, the reference point coincides with the location of the event spoken about. 'Perfect' tense meanings are created when the reference point is separated and moved away from the event time, thus altering the viewing of the temporal location of the event even though the event's actual location with respect to the deictic centre remains the same.
Posterior temporal relationships obtaining in a 'perfect' context occur when the reference point is moved away from the event time. There are various logical possibilities for locating the reference point with respect to the other two points, though none of them seem to be typically grammaticalised as separate tenses.
Typically, for a tense value to be labelled as Future Tense, the tense meaning has to minimally express the posterior temporal relationship, although it may additionally express other temporal, aspectual, or modal meanings.