Data types

[Svante Schubert <Svante.Schubert@Sun.COM>]

As we have discussed data types on our last call, I would like to ask 
for agreement (or corrections) on the summary below:

What we already have in ODF:
======================
In the ODF spec beyond "6.7.1 Variable Value Types and Values" we 
specify 7 value types in the OpenDocument format.
Two - 'date' and 'time' - are explicitly mapped to W3C Schema datatypes 
(http://www.w3.org/2001/XMLSchema-datatypes).

But 3 further types could be mapped to W3C types (i.e. float, boolean 
and string)
(see graph about existing W3C schema types - 
http://www.w3.org/TR/xmlschema-2/#built-in-datatypes) .

The two remaining ODF types 'percentage' and 'currency' have no relation 
to W3C.
I am not aware of any existing URI representation for those two types.

What I propose based on our discussion:
============================
For all ODF elements where RDF related attributes (e.g. meta:about) 
might be used, the attribute 'meta:value-type' declares the data type 
hold by the element.
The data type is described by an IRI. Any IRI might be used, but it is 
recommended to reuse the existing W3C Schema data types 
(http://www.w3.org/2001/XMLSchema-datatypes).
The existing data types of OpenDocument, as described in "6.7.1 Variable 
Value Types and Values" should be expressed by using the original 
identifier string in conjunction with the office namespace and a hash. 
For example, 'urn:oasis:names:tc:opendocument:xmlns:office:1.0#percentage'.

In addition the attribute style:data-style-name might be used for 
formatting as described in "6.7.7 Formatting Style".

Especially for the element 'meta:label' the attribute 'meta:value' might 
be used to add the original meta data value to the element, which in 
general differs from the element content (the label) to be shown.
As the attribute value of 'meta:value' depends of 'meta:value-type' any 
string is in general allowed.

Svante.