Term due to McTaggart for the ordering of events in respect of past, present, and future. McTaggart's proof of the unreality of time argues first, that this ordering is essential to capturing the nature of time (see b-series), and secondly, that it involves a contradiction, since being past, present, and future are incompatible properties, yet each event has to have all three: any event will eventually have been each of future, present, and then past. It is sometimes thought that this is no more contradictory than a house being both near (to me) and far (from you). But the heart of McTaggart's complaint is that distinctions of tense belong to one or another changing perspective, yet there is something improper about thinking of reality itself as essentially perspectival.
http://librivox.org/unreality_of_time/ McTaggart's ‘The Unreality of Time’
http://people.stfx.ca/wsweet/mctaggart.html A list of internet resources on McTaggart's philosophy, including a bibliography