Use this section for verbal auxiliaries, affixes, adverbs, and particles that indicate relational tenses. Relational tenses describe situations where the reference time is not the same as the moment of speech. They may be combined with any of the tenses, either in the same morpheme or in combinations of morphemes. 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.