🚀 go-pugleaf

Here is a summary of responses from my question of how to represent 1990 in
Roman numerals:

  1.  The Romans themselves didn't use the "subtraction trick" (i.e., 4 was
      IIII not IV).  -- Raymond Chen, Mike Albaugh's Latin teacher/basketball
      coach, and Don Hosek.

  2.  Although nobody could provide a solid reference (such as a style
      manual), the general consensus is that you should only subtract if
      the smaller unit is an order of magnitude smaller than the larger unit
      (i.e., 9 = IX, and 99 = XCIX not IC).
      -- Raymond Chen, Ken Yap, John Shipman, Gerald Edgar, Mike Albaugh

Thus 1990 is MCMXC, and 1999 will be MCMXCIX, and TeX was right (of course :-).

Aid.  (Standard disclaimers).