Ah.....
This is really a big cultural difference, and I think there's a need of clarification on why the system designer put "AD" here.
In Taiwan, our society doesn't have a generally speaking Christian
Religion background. In our daily life, we usually count year in the
"19XX", "200X" way as same as most parts of the world, and both in the
way "year of Republic of China". For example, I was born in the 66
"year of Republic of China". This year is the 96 "year of Republic of
China".
Whatever, the name "year of Republic of China" is another big
politically controversial issue for Taiwanese and Chinese communities
all over the world. In Wikipedia Chinese Version, there is someone
named "Republic of China 95 year". He did editing wars and got blocked
several times.
Therefore, the designer just wanted to make it clearer that "Don't fill
in the number of year of Republic of China, but 19xx or 20xx". I
don't think there was any intention to cause a lift of debates.
Thanks
THD