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Re: We need a META schema registry!

From: Dan Connolly <connolly@w3.org>
Date: Thu, 27 Mar 1997 18:12:18 -0600
Message-ID: <333B0CE2.3731D91F@w3.org>
To: advax@triumf.ca
CC: www-talk@w3.org, meta2@mrrl.lut.ac.uk, swick@w3.org
Andrew Daviel wrote: 
> The Web needs a Metadata registry, IMO.

The Web _is_ a metadata registry, IMO. And that's the
way it was designed by TimBL (see below).

> In HTML, many organisations and individuals are starting to generate
> Metadata using the META tag without any agreement as to what the
> data means. While I applaud the effort to generate useful metadata,
> a proliferation of unregistered types is going to dilute its utility
> greatly.
> Given that many organisations will want to use private metadata, and that
> particular disciplines have their own metadata, a single global repository of
> all metadata types is clearly unworkable.

Quite the contrary! Each organization that wants to
define a metadata field (or schema of fields) need only
assign it a URL, and (optionally) publish the specification
at that URL.

They're already doing just that, in fact. I started maintaining
a list of schema URLs at

So far, I have:

> Examples of metadata with schemas and subschemas:
> <META NAME="DC.Author" CONTENT="Oscar Wilde">
> <META NAME="MCF.versionNumber"> CONTENT="1.3b">
> <LINK REL="DC.Author" HREF="http://andrew.triumf.ca/~andrew/">
> <A REL="MCF.helpPage" HREF="http://some.org/gxt/help.html">Help on GXT</A>
> The schemas DC (Dublin Core), MCF (Meta Content Format) etc.
> would be registered with the top-level registry. The organisation
> registering the schema would be responsible for documenting it.

Your example could be written:

<META NAME="http://purl.org/metadata/dublin_core_elements#Author" 
	CONTENT="Oscar Wilde">

Folks are hammering out various syntactic variations on
that theme, but the semantics are the same:

Tim Berners-Lee 
Date: Januray 6, 1997 


A space for attribute names 

It is appropriate for the Web architecture to define like this the
topology and the general concepts of links and metadata. What
about the significance of individual relationships? Sometimes, as
above, these are special, defined in the architecture, and having
an architectural significance or a significance to the protocols. In
other cases, the significance of relationships or indeed of
attributes is part of other specifications, other design, or other
applications, and must be defined easily by third parties.
Therefore, the set of such relationship and attributes names must
be extremely easily extensible and therefore extensible in a
decentralized manner. This is why 

 the URL space is an appropriate space for the definition of
 attribute names. 

For background reading, see also
the "Naming: A social and contracual[sic] Issue" section of

and my notes on catalog searching:

Dan Connolly, W3C Architecture Domain Lead
<connolly@w3.org> +1 512 310-2971
PGP:EDF8 A8E4 F3BB 0F3C FD1B 7BE0 716C FF21
Received on Thursday, 27 March 1997 19:12:26 UTC

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