The date/time formats defined for U.S. and other locales don't include any era information. It's not possible for users to distinguish B.C. and A.D. dates.
See 4482478 for details.
Comments
EVALUATION
It may be useful to add the era to the FULL date formats.
norbert.lindenberg@Eng 2001-07-27
IBM's ICU also doesn't have era in the FULL date formats. So, we will not fix it at this time.
###@###.### 2003-09-22