http://docwiki.embarcadero.com/Libra...stem.TDateTime
Zitat:
TDateTime supports negative values too. The negative spectrum mirrors the positive one exactly. As such, a value of Now (positive) is exactly the same as its negative value--Now. You should use negative TDateTime values with care. Incorrect use of negative values can lead to various problems.
Zitat:
When working with negative TDateTime values, computations must
handle time portion separately. The fractional part reflects the fraction of a 24-hour day without regard to the sign of the TDateTime value. For example, 6:00 A.M. on December 29, 1899 is –1.25, not –1 + 0.25, which would equal –0.75. There are no TDateTime values from –1 through 0.
Wenn du solche wilden Datumsbereiche betrittst würde ich persönlich mir das nicht antun und ein eigenes Datumsformat und nicht TDateTime nehmen.