The Free On-line Dictionary of Computing (30 December 2018):

Didot point

    A variant of the point, equal to 0.3759 mm, or
   1/72 of a French Royal inch (27.07 mm), or about 1/68 inch.
   Didot points are used in Europe.  This unit is named after the
   French printer François Ambroise Didot (1730 - 1804) who
   defined the "point-based" typographical measurement system.

   (2002-03-11)