NSA Time

NSA time corresponds with earth time, such as in the books or Narnia, Narnia time and earth time also intersect. A NSA year is one quarter of a School year. So to get NSA years from Earth years:

([current Earth year] - 1998 ) * 4 = NSA years

from NSA to Earth is:

[NSA years] divided by 4 + 1998 = Earth time