Dobrou odpověď na ohraničení století už kdysi vymysleli v NISTu (jedna z největších světových autorit v oblasti "timekeepingu" - americký Národní úřad pro standardizaci a technologie). První věta hovoří za vše.
On what date will the 21st century begin?
This is a date that no organization, including NIST, has the authority to regulate. However, one logical answer to the question is that because there was never a year "zero," and a century must have 100 years, then each century must begin with a year numbered "1." In other words, the 20th century should be considered as ending on Dec. 31, 2000, and the 21st century as starting on Jan. 1, 2001.
However, human nature being what it is, most of us will still opt to have that "once-in-a-century" New Year's Eve bash on Dec. 31, 1999.