[LEAPSECS] Leap second mess at NASA

[Zefram]

Daniel R. Tobias wrote:

>"Current CDF_Epoch time scheme is nominally continuous Gregorian time 

>from 0AD"... unfortunately for them, there wasn't actually any such 

>year as "0 AD", since the real years went straight from 1 BC to AD 1.


"AD 0" is a perfectly meaningful label.  It refers to the year before AD
1; that year is also known as 1 BC.  Likewise, AD -1 is 2 BC, and so on.
This kind of year numbering is common in astronomy, and was written into
the latest version of ISO 8601.  The use of AD year numbers below 1 is,
of course, contrary to convention in less technical contexts.

-zefram