On Tue, 23 Nov 2010 11:02:48 -0500, Ray Denenberg, Library of Congress wrote
> The problem is that 'x' is often used to mean "any and all digits",
>  so that "8xx" literally means "all values 800 through 899" when 
> what we want it to mean is "one specific value in the range of 800 
> through 899 (inclusive)". 

On Mon, 22 Nov 2010 19:30:15 +0100, Jakob Voss wrote

> Wikipedia already uses this notation, which should be argument 
> enough, for instance:

The said Wikipedia page sets 19xx to REDIRECT to 20th century which is Ray's
suggestion of "any and all digits". 

196x in Wikipedia

is not even defined. So its not all that consistent and not part of their
policy--- as if their policies truly mattered to us--- but a page contributed
by a young advertising website copyrighter named Nicholas Moreau (aka "Zanimum").

    * (cur | prev)  16:33, 20 March 2007 Zanimum (talk | contribs) (26 bytes)
(←Redirected page to 20th century) (undo)
    * (cur | prev) 16:32, 20 March 2007 Zanimum (talk | contribs) (19 bytes)
(←Redirected page to 1900s)

Please note that originally the page redirected to 1900s. That page was
created in 2007. A stub for 18xx was created in 2005 and 20xx in 2008.

Note also that other than 18xx, 19xx and 20xx I don't think other pages have
been created. I found nothing under 196x or 1x66 or x999. When you look at
196x or 1x66 or x999 what do you immediately think?

While our expectations of 19xx when viewed as a date lead us to assume that x
is some single non-negative decimal integer, I would even argue that x has not
been specified to be a non-negative single digit decimal integer and thus,
following the abstract model, could be anything.. an argument, I think, that
also holds against the 'u' and space ('#') of the MARC domain. In many
computer textbooks the convention n for non-negative decimal, o for octal, h
for hexadecimal etc. single digit integers are popular. I don't suggest these. 

We want, I suggest, to be able to express both the intent of 19xx as
representing the 20th century and 19xx as representing a specific year date in
the 20th century. 

We have, in contrast to the bibliographic date example, two different
kinds of vagueness as well as states of knowledge:

19?? where it can be meant sometime in the 1900s (one specific value that
just not known) and 1900s which can mean (but does not need to) all values
"1900 through 1999".

We need also to distinguish between expressions about the 1900s that refer to
the 20th century and those that refer to the first decade of that century.
While the colloquial use of the expression "1900s" typically refers to the
turn of the 19th to 20th century the expression "1300s" more typically is used
to address the 14th century than its dawning decade.

In the bibliographic model there is also the "unknown" (marked | and not 'u')
to denote something that might be known but has not yet been collected.

So for 19?? we have three semantics for '?':
1) A specific value currently unknown. Example: 195? to represent a book known
to be published in the 1950s but with unknown year (I actually have a few
books that don't have copyright dates but from later additions know, more or
less, roughly when they were published)
2) A specific value not yet collected: to be filled in at a latter time
3) A implicit expression of lesser precision. The 1950s, for example,
referring not to a specific year but to a view of dates roughly in decades
just as 1929 may refer to an explicit event in 1929 (such as the 29 October
stock market crash) or a series of events such as the "Great stock market
crash" (spanning from no later than 3 September 1929 when the Dow hit its high
to no later than 1932 when the market bottomed out at under 10% of value), to
the whole of the year or to a watermark (the Great Depression started in 1929).

  I think we need to kick around another 
> character, if 'u' is considered unacceptable.  I find it unfortunate,
>  because I think that 'u' is the most natural character to use for 
> this purpose.

I don't find it terribly natural but accept its use case in MARC21 which is, I
think, sufficiently strong to warrant its use here.


Edward C. Zimmermann, NONMONOTONIC LAB
Basis Systeme netzwerk, Munich Ges. des buergerl. Rechts
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