Re: [xml-dev] Could someone give a precise definition to these terms and the relationships between them?

Here you go:

Modeling Primitives:  In general, the term "primitive" indicates an
entity that is not composed of other entities - for example, a data type
of "string".  This can apply to modeling (such as UML modeling) as well.

Metadata: Data about data.  XML tags represent metadata.

Concept Constructors:  This term is used in a field called "Description
Logic".  DAML+OIL [1] has a large collection of concept constructors,
and Description Logics (DLs) are characterized by a set of constructors
provided for building complex concepts and roles from simpler ones.

Hope that helps,
Joe Chiusano
Booz | Allen | Hamilton

[1] http://www.w3.org/TR/daml+oil-walkthru/

Collin wrote:
> 
> modeling primitives,
> metadata,
> concept constructors