Antoine Leca wrote: . . . TIME_TAI *or* TIME_UTC (as defined by Markus, with the added point that the calendar should be the proleptic Gregorian). Markus Kuhn replied: Question: What precisely does "proleptic" mean and where is it defined? . . . (I suspect it means "extended before the time it was defined", but would like to get a confirmation and reference.) Short answer: My understanding agrees with Markus's suspicion. Longer answer: I looked up the word in two respected American English dictionaries: the Webster's Ninth New Collegiate Dictionary (1985), and the American Heritage Dictionary (New College Edition, 1976). Webster's New Collegiate defines "prolepsis" (a noun) as "the represen- tation or assumption of a future act or development as if presently existing or accomplished", or "the application of an adjective to a noun in anticipation of the result of the action of the verb". "Proleptic" is listed as the corresponding adjective. The American Heritage defines "prolepsis" as "the anticipation and answering of an objection or argument before one's opponent has put it forward", or "the use of a descriptive word in anticipation of the act or circumstances that would make it applicable". It lists both "pro- leptic" and "proleptical" as adjective forms. Both dictionaries say the word is derived from Greek "prolambanein" (to take beforehand) < "pro-" (before) + "lambanein" (to take). Webster's New Collegiate says the first recorded use of the word in English was in 1578. So, the "proleptic Gregorian" calendar would be the result of extending the Gregorian calendar back into the past, before it came into use in a given location, or even before it was invented. My sense (as an educated native speaker of American English) is that "proleptic" and "prolepsis" are not commonly known or used by the aver- age English-speaking person. English is, of course, replete with such words, known primarily by authors, orators, and Scrabble players. Rich Wales richw@webcom.com http://www.webcom.com/richw/