Carl,

I had a quick look at your paper today.  More detailed comments will follow
, but my first reaction was that it lacks an overview to motivate the
concepts that follow.  Here is my attempt at an introduction.  Please feel
free to extract anything that is useful.

Bill

=======

Overview

In March 1995, OCLC hosted a meeting to discuss metadata for items of
digital information.  The major result of that meeting was a list of
thirteen metadata elements that can describe a wide variety of items.  This
list has become known as "the Dublin Core".

A year later a follow up meeting was held at the University of Warwick to
review progress and plan future steps.  Three key concepts came out of this
meeting.  Collectively, they have been nicknamed "the Warwick Framework."

Metadata Packages

Although many groups are building information services with metadata drawn
from the Dublin Core, every group is adding extra metadata elements.  The
additions may be subject specific (e.g., for geo-spatial data), technical
(e.g., formats or protocols), structural (e.g., links to show relationships
between complex objects), or business related (e.g., terms and conditions
for usage).

To handle this need, the Warwick meeting proposes a set of metadata
packages.  For example, the Dublin core is one package; another might be
the terms and conditions package.  An information service can select one or
more packages to provide metadata for a set of objects.

This approach has several advantages over selecting individual metadata
elements from a very long list of elements.  Packages can be very
different.  For example, a package that expresses relationships among
objects might use abstract data structures.  A  reasonably small list of
well defined packages is hoped to enhance interoperation and lead towards
standardization of practices.  In addition, as described below, packages
allow flexibility in the development of a security architecture.

Security

When a digital object is accessed over a network, there are many occasions
when a supplier wishes to make only part of the metadata accessible to
specific users.  For example, an organization may need to have access to
technical metadata in order to store and transmit information, but, to
avoid potential liability, may explicitly desire not to have access to
metadata that describes content.  A commercial organization may wish to
provide some metadata openly, but require authorization before giving
access to other metadata.

These objectives can be achieved by providing each metadata package with
its own security.  Access controls on each package can be different.

Representation of Metadata

There will undoubtedly be many different representations of metadata within
repositories.  For example, the metadata for a digital item can be embedded
within the item or external but associated.  Much of the work on
repositories uses the concept of a "digital object", in which the metadata
and the data are both stored within a repository without the details of the
storage mechanism being known externally.

Formats for exchanging metadata between systems need to be clearly defined,
flexible, yet easy to use.  Preliminary work carried out during the Warwick
meeting convinced many of the people attending that SGML provides a
suitable format to represent metadata packages.  The meeting considered
that Web pages in html format are such an important special case that they
deserve special attention.  The meeting proposes a syntax based on the html
"meta" tag.