O.K., I concede defeat!  (Well, maybe...)

I've always seen and understood time lines to include a zero, with the
zero depicting the convergence of the first year B.C. (depicted by the
space to the left of the zero) and the first year A.D. (depicted by the
space to the right of the zero).  Each mark indicates the convergence of
two years; the spaces are actually the years.  With that assumption, my
calculations work perfectly.

However, I've tried researching this further and discovered that there
are many ways to calculate the years.  Chiefly, historians do not
include the zero on their time lines. There seems to be some confusion
where the convergence lies on the number line.  Some say A.D. 1 to 1
B.C. is the first year B.C. and A.D. 1 to A.D. 2 is the first year A.D.;
others seem to say that 1 B.C. to A.D. 1 is the first year A.D.   Either
way does, indeed, bring my system up short by a year.

Astronomers and mathematicians, however, do include the zero in their
calculations.  I have also seen many historians include the zero.  (Are
these historians bucking the system, are they ignorant of the rules, or
do they have a rational reason for including the zero?)  Under these
systems, I believe we're back to my system of calculation.

So, I am officially confused!  If someone knows a definitive, historical
source (other than Wikipedia) that can shed some light on this area, I'd
be very interested to do further research.  An internet link would be
ideal since I don't have access to a good library.  However, I'm not
immune to tracking down a good book, either!

Thanks for all the input!

Carolyn II