Re: [xml-dev] Value spaces are cool! I wish for a cross-product(aggrega

[John Cowan <cowan@mercury.ccil.org>]

Costello, Roger L. scripsit:

> Is there another option (beside XML Schema) for expressing value spaces
> and aggregate value spaces? Can aggregate value spaces be expressed
> using Relax NG?

RELAX NG allows for multiple datatype libraries.  The only library
required by the spec is a trivial one containing "string" and "token"
types.  However, most RNG tools support at least the XSD library, and
some can be extended to support libraries written in a conventional
programming language.  DTLL is a forthcoming XML-based language for
declaring your own datatype libraries without having to write code.

There are a few minor incompatibilities between the RNG view of the XSD
library and its own view:

    The whiteSpace facet is not supported.

    The enumeration facet is not supported (use a choice of values
    instead).

    Multiple pattern facets are an implicit intersection rather than an
    implicit union as in XSD 1.0.  In XSD 1.1, they are also an implicit
    intersection.

    The NOTATION datatype is treated as a synonym for QName, because
    RELAX NG does not have notation declarations.

    The ID, IDREF, and IDREFS types must be used in a DTD-compatible way.
    That is, they can only be used as attribute types, and the attributes
    of a specified element name have to share the same IDness across
    all uses of that element name.  This arises particularly when you
    specify that a wildcard attribute (which must always be of type
    string) and an ID attribute may both appear on the same element.
    The wildcard must be modified to exclude the ID attribute.

-- 
It was impossible to inveigle           John Cowan <cowan@ccil.org>
Georg Wilhelm Friedrich Hegel           http://www.ccil.org/~cowan
Into offering the slightest apology
For his Phenomenology.                      --W. H. Auden, from "People" (1953)