Use this domain for verbal auxiliaries, affixes, adverbs, and particles that indicate tense (also known as temporal deixis)--the time of a situation (event, activity, or state) in relation to a reference point, which is usually the time of utterance. The following definitions are taken from Bybee, Joan, Revere Perkins, and William Pagliuca. 1994. The evolution of grammar. Chicago and London: University of Chicago Press.