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Primitive Datatypes of XML Schema (boolean, float, double)

From: Ofer Brandes <brandes@mintech.co.il>
Date: Sun, 30 Jan 2000 17:11:34 +0200
Message-ID: <21ADF5CD284FD311AC0C00E01890310D057074@MAILSERV>
To: "'www-xml-schema-comments@w3.org'" <www-xml-schema-comments@w3.org>

After a few months of working on other issues, I have recently returned to
see what is new with XML, and I'd like to express my appreciation for the
progress made with XML Schema. I see in the drafts of 17 December 1999 a
very good foundation for a solid semantic basis, which was so missing in XML
for a long time.

I have, though, a couple of questions, and excuse me if they represent the
ignorance of a new-comer to this community:

(1) boolean datatype (section 3.2.2 of http://www.w3.org/TR/xmlschema-2/)

I think 'true' and 'false' are not enough for the boolean value space. In
addition we need at least 'unknown' (similar to NAN for numeric types). This
value enriches the expressive power of the datatype, and can easily be used
in boolean computations (e.g. 'true' or 'unknown' evaluates to 'true').

If we don't have it, there will be cases where we either force arbitrary
'true' or 'false' values or bypass boolean by user-defined datatypes with
richer expressive power.

(2) float and double datatypes (sections 3.2.3 and 3.2.4 of

It is not clear to me why these two are considered "Primitive Datatypes".
Why not define a single primitive datatype representing real numbers (the
mathematical concept), and then derive two (or more) generated datatypes
according to the needs of IEEE-754 or any other need?

My feeling is, that the basic datatypes should be as abstract as possible,
which will increase both their usability (especially by non-programmers) and
stability (as representation standards change over the years).

I'll be glad to get feedback from those of you who are part of this
important initiative.

-- Ofer
Received on Sunday, 30 January 2000 10:09:51 UTC

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