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

time shifting

    A technique used to work around problems due to
   the Year 2000 and the "millennium bug".  Time shifting
   involves translating date fields in a database back by a fixed
   number of years to avoid year 2000 problems with the database
   management system.

   Typically dates are shifted back 28 years so that the occurrence
   of leap years and days of the week match with the actual year.

   (2003-08-15)