Good question about century, Dave. (Finally had a chance to think about it,
sorry, been out two weeks.)
I think "first century, AD" is straightforward, it's '00'. The guidance
from 8601 is not explicit but seems to strongly imply that the century of
any four-digit (AD) year is represented by its first two digits, so '00'
would represent the century for the years 0001 through 0099.
The second question is a problem. 8601 gives no guidance whatsoever that I
can find. I'm perfectly willing to defer to anyone here who knows the
authoritative answer. in lieu of that, I'm going to offer a tentative
I have updated the table to reflect these.
My reasoning is as follows. I think it is safe to conclude that we can
narrow the choices to '-00' and '-01'. One could argue against '-00' on the
basis that zero is neither positive nor negative and could argue in favor of
'-01' on the basis of mathematical calculation. However, I suspect that
these centuries are not used much for mathematical calculation, and that
'00' and '-01' could be viewed as two different strings, rather than
integers. And I think that using '-00' is logically consistent with the way
century is derived for AD years (i.e. via truncation).
But if someone has a convincing argument to the contrary I'll change it.
From: Discussion of the Developing Date/Time Standards
[mailto:[log in to unmask]] On Behalf Of Reser, Dave
Sent: Monday, September 20, 2010 2:24 PM
To: [log in to unmask]
Subject: Re: [DATETIME] EDTF Features list
Thanks for providing the features table. We think it solves almost all of
our problems, but we have a question on recording two specific centuries.
Section 2, line 201 for Century indicates how to record centuries (e.g., 19
for the 20th century), but we are perplexed about:
First century (AD/ACE)
First century (BC/BCE)
Any advice is appreciated.
LC Policy & Standards Division