Gregorian calendar

The Gregorian calendar was a dating system used on Earth. Consequent to the British changeover from the Julian calendar to the Gregorian, eleven days — 2 September through 14 September 1752 — were "lost". These days, as experienced in London, were purchased by the Faction Paradox and became their heartland, known as the Eleven-Day Empire. (EDA: Interference - Book One)