On Tue, 30 Aug 2011 15:13:25 -0400, Ray Denenberg, Library of Congress wrote
> From: [UTF-8?]SaaÅ¡ha Metsärantala
> > The BNF excludes dates such as
> > 199u-uu
> > at level one.
> > At 102, such a date is not present in the "Examples" column, but it is
> > not excluded as of the "Syntax/rules" column. In such a date, no "u" is
> > "internal" and therefore, I consider that such a date is "level one".
> My intent was pretty much as expressed in the BNF, though perhaps not
sufficiently described in the prose, so that can be improved. The intent is
that level 1 unspecified is one of the following:
Since u is a placemarker (to be filled in a some later date).. why restrict
its use? Recall "1990-uu" says (an event took place in) a month in 1990 that
will be "filled in later" (e.g. precision of month).. versus "1990" that
says (an event took place in) 1990 (e.g. precision of year).
> 1. a year with one or two (rightmost) unspecified digits, e.g. 199u or
19uu. Year only.
> 2. year specified but month unspecified. e.g. 1990-uu (And in this
case, no provision for just one of the month digits unspecified, e.g. 1990-
1990-12-0u seems if we are going to have u as a legitimate expression.
Imagine I want to document a date I know took place at the start of Dec.
1990 but I'm not sure if it was the 1st, 2nd or 3rd of the month.. and I
want to check.. The expression "1990-12-0u" seems fine and dandy... later
when I've checked that it was the 3rd I'd fill it in.. That's why I might
write "1990-12-0u" and not "1990-12" with the non-expressed (private) intent
of expanding the date when I have the data (and time to attend to the task).
I would argue that u as blanks to be filled in.. should be allowed wherever
anyone might see fit to use them. I personally might not ever see the need
for an expression such as "uuu2-12-22" but who am I to say "no no"..?
The "rightmost" rules were about---- and should be limited to--- precision,
e.g. "x". xxx2 makes no sense. uuu2 does.
(that said the expression "1990-12-0x" does make sense to be as does all the
expressions "from right to left")
> 3. Year and month specified, day unspecified (And similarly no provision
for just one digit of the day unspecified, as in 1990-12-0u.)
Beware the use of the predicate "unspecified". In the date "1990" neither
the month or day are specified but its something quite different from "1990-
uu-uu". If one can specify the month of a date that is expressed in years
then the date has at least month precision.. similarly if one specify the
month and day it has day precision.. "can specify" and "specify" are not, I
must stress, the same. With "1990-12-uu" I explicitly state that I "can
specify" the day but has not yet--- I plan on filling in the blanks..
With "1990-12" I say that I can't--- obviously with more information....
> 4. Year specified, day and month unspecified.
> If anyone thinks this is not sufficient please provide a use case. I
will add the above description to the prose.
> > internalUnspecified = ( year "-uu-" day ) | ( yud "-" ( monthDay |
> > ( month "-uu" ) | ( "uu-" day ) ) )
> I've changed it to:
> internalUnspecified =
> year "-uu-" day
> | yearWithOneOrTwoUnspecifedDigits "-" IUMonthDayPart
> IUMonthDayPart =
> | month "-uu"
> | "uu-" day
Edward C. Zimmermann, NONMONOTONIC LAB