Future tense assigns a value 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. Modeling of this distinction originates from [Reichenbach 1947: 288], 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. [Kibort 2008c: 5]