From: Edward C. Zimmermann
> I think the predicates for uuu-uu-uu--- and for that matter any use of
> u--- should be opened. Unspecified means that something is perhaps
> known but not expressed. Unknown means that the something is not known.
> Undated does not mean unknown date nor unspeficied date but expresses
> that no date has been assigned.

'u' no longer means "unknown", it means "unspecified".  I don't know that
the distinction between "undated" and "unspecified" is necessary/meaningful
for our purposes. So far, it seems to me that the use case presented is
satisfied without making that distinction.  I would like to see separate use
cases before we pursue this further.

> This goes back to the dicussion I tried to open some months ago on
> readability and precision. Does 1900-uu mean something different than
> 1900?

I believe this depends on the definition of the element that you are
assigning this value to, which would be in the application's data
dictionary, and is out of scope. You might have a data element 'startMonth'
in which case by supplying the value 1900-uu you assert that it was "some
month in 1900".  On the other hand you may have a data element
'publicationYear' in which case supplying a value of 1900 would be more
appropriate that 1900-uu. 

> In this light the following:
> - uuuu
> - uuuu-uu
> - uuuu-uu-uu
> - uuuu-uu-uuTuu:uu
> are not the "same".

Ok, they are not the same. Similarly I would say that which one of these
values is supplied would depend on the definition of the data element that
you are assigning the value to.