I am not completely certain that they are semantically identical.... 
thinking a bit.. I am convinced that they are NOT identical..
{1950..1959} means the set (all of) dates 1959 through 1959. It is an array 
of dates expressed with a precision of year.
The expression 195x, by contrast, is neither an array nor an expression with 
a precision of year but a date with a precision of 10 years. 
An ordering function however should return 
    "{1950..1959}" == "195x" 
as in any comparison the most coarse precision should be the basis for 
comparison, e.g. the set of 1950..1959 read with a precision of decade (10 
years) is just the expression "195x".
Its, I think, conceptually not really different from expressions such 
as "1999" or "1999-02"--- for that matter even "1999-02-08"--- compared 
to "1999-02008T12:12Z"... In this light--- just as I don't see
  "{1999-02008T12:12Z..1999-02008T12:12Z}" as identical with "1999-02-08"--- 
the epressions are neither identical nor even, differing in precision, 
semantically equivalent....


On Mon, 27 Jun 2011 15:05:48 -0400, Ray Denenberg, Library of Congress wrote
> From: [UTF-8?]SaaÅ¡ha Metsärantala
> > - in such a context - would be the semantic difference between
> > 
> > 199x
> > 
> > and
> > 
> > {1990..1999}
> > 
> > If there is such a semantic difference, I suggest to clarify it in the
> > specification.
> 
> There is no semantic difference.


--

Edward C. Zimmermann, NONMONOTONIC LAB
http://www.nonmonotonic.net
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