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Hi Rebecca,

    I'd briefly commented on this in an earlier post.  On further
reflection, the relationship between authorities and XML namespaces
seems (to me) even closer.  Just as an XML schema defines some or all of
the contents of an XML namespace, a <madsCollection> (or just <mads>)
defines the contents of an authoritative list.  The authority attribute
is analogous to the xmlns pseudo-attribute.  The interpretation of a
<mads> or <related> element with no authority="" would be, as with
namespaces, it inherits the authority of its closest ancestor with an
authority="".
    Both for backwards-compatibility with MODS 3.0, and for
convenience, there should be a mechanism to alias authority URIs, where
some aliases are reserved for LoC use to specify standard lists, like
the namespace prefix "xml:" is fixed by the W3C.  For example, "marcgt"
could be a predefined alias for the authority URI
"http://www.loc.gov/marc/sourcecode/genre/genresource.html".  Maybe
better would be to reserve values for *non-LoC* use, since the lists of
existing authorities are already so extensive (33 for genre alone).  All
user-defined authority URI aliases must begin with a capital letter,
say, or with the string "local:".

--Andy

>>> [log in to unmask] 2004-06-23 09:49:39 >>>
[snip]

As for authority, we made it optional for because there could be a
record
for an entity that is not controlled by a specified authority list.
However, we could use something like "local" as a value for that. As
for
having a defined list of values, we maintain lists of thesauri and
authority files which have hundreds of entries. Also, we add new values
to
these regularly, so wouldn't want to have to maintain a specified list
in
the schema. Couldn't we just use a URI to reference these lists of
values?

Rebecca
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
^^  Rebecca S. Guenther                                   ^^
^^  Senior Networking and Standards Specialist            ^^
^^  Network Development and MARC Standards Office         ^^
^^  1st and Independence Ave. SE                          ^^
^^  Library of Congress                                   ^^
^^  Washington, DC 20540-4402                             ^^
^^  (202) 707-5092 (voice)    (202) 707-0115 (FAX)        ^^
^^  [log in to unmask]                                          ^^
^^                                                        ^^
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^


> ---------- Forwarded message ----------
> Date: Sat, 05 Jun 2004 12:18:54 +0200
> From: Stefano Mazzocchi <[log in to unmask]>
> To: simile general <[log in to unmask]>
> Subject: Re: Fwd: [MODS] MADS: XML schema for authorities
> Resent-Date: Sat,  5 Jun 2004 06:18:58 -0400 (EDT)
> Resent-From: [log in to unmask]
>
>
> MacKenzie Smith wrote:
>
> >
> > FYI -- this is possibly relevant to the work on name matching since
much
> > of the name data comes from MARC name authority records, and this
new
> > XML schema is a substitute for that format. It's still XML, but it
> > should make conversion to RDF a lot more straightforward if it's
adopted
> > for the big name authority files like the Library of Congresses.
>
> Not sure how "straight forward" this could be.
>
> I've looked at the schema and it's a very general one, it's used to
> encode a bunch of things with the same exact elements and all the
> semantic information is encoded in attribute values.
>
> For example:
>
> <?xml version="1.0" encoding="UTF-8"?>
> <mads xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
>        xsi:noNamespaceSchemaLocation="/mads-v.3.xsd">
>       <authority>
>         <topic authority="LCSH">Computer programming</topic>
>       </authority>
>       <refs>
>         <ref relatedType="broader">
>               <topic>Computers</topic>
>         </ref>
>         <ref relatedType="narrower">
>               <topic>Programming languages</topic>
>         </ref>
>         <ref relatedType="otherRelated">
>               <topic>Systems Analysis</topic>
>         </ref>
>       </refs>
> </mads>
>
> <?xml version="1.0" encoding="UTF-8"?>
> <mads xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
>        xsi:noNamespaceSchemaLocation="/mads-v.3.xsd">
>       <authority>
>          <geographic authority="naf">Ceylon</geographic>
>       </authority>
>       <refs>
>          <ref relatedType="later">
>               <geographic>Sri Lanka</geographic>
>          </ref>
>       </refs>
> </mads>
>
> All the semantics is in the attribute values relatedType="" and
> authority="".
>
> relatedType="" values are constrolled by the schema, but the
attribute
> itself is optional.
>
> authority="" values are *not* controlled by the schema and the
attribute
> is optional.
>
> Converting this schema to a useful RDF is algorithmically impossible
> since too much information is kept implicit and/or optional.
>
> The only graph topology that can be inferred from this MADS schema
is
> that some literals have some sort of relationship with others
(optinally
> labelled) and that this relationship is optionally backed up by a
literal.
>
> If all the attributes were required and all the attributes value
were
> controlled and restricted by the schema, then the migration could be
> straightforward.
>
> HTH
>
> > MacKenzie
> >
> >> Date:         Fri, 4 Jun 2004 09:34:04 -0400
> >> Reply-To: Metadata Object Description Schema List <[log in to unmask]>
> >> From: "Rebecca S. Guenther" <[log in to unmask]>
> >> Subject: [MODS] MADS: XML schema for authorities
> >>
> >> In response to numerous requests, the Library of Congress'
Network
> >> Development and MARC Standards Office has drafted an XML schema
for an
> >> authority element set that may be used to provide metadata about
agents
> >> (people, organizations), events, and terms (topics, geographics,
genres,
> >> etc.).  This Metadata Authority Description Schema (MADS) was
created to
> >> serve as a companion to the Metadata Object Description Schema
(MODS).
> >> As such, MADS has a relationship to the MARC 21 Authority format,
as MODS
> >> has to MARC 21 Bibliographic-- both carry selected data from MARC
21.
> >> There is a high level of compatibility between the MADS and MODS
schemas.
> >> MADS is expressed using the XML schema language of the World Wide
Web
> >> Consortium.  Note that once the schema is finalized, a few changes
may be
> >> made to MODS for consistency. An example is that MADS uses the
term
> >> "event" instead of "conference".
> >>
> >> The MADS draft schema is now available for broad review to inform
its
> >> completion. Based on input from prospective users, the schema will
be
> >> revised and made available for experimentation. The review period
will be
> >> between June 4 and July 16, 2004.
> >>
> >> The Web site is at:
> >> http://www.loc.gov/mads
> >> Included is the XML schema itself, a document describing the
purpose of
> >> MADS and details about definitions of the most important elements,
and an
> >> outline of elements and attributes. A mapping to the MARC 21
Authority
> >> Format will be available shortly.
> >>
> >> We look forward to comments from prospective users about this new
schema.
> >>
> >> ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> >> ^^  Rebecca S. Guenther                                   ^^
> >> ^^  Senior Networking and Standards Specialist            ^^
> >> ^^  Network Development and MARC Standards Office         ^^
> >> ^^  1st and Independence Ave. SE                          ^^
> >> ^^  Library of Congress                                   ^^
> >> ^^  Washington, DC 20540-4402                             ^^
> >> ^^  (202) 707-5092 (voice)    (202) 707-0115 (FAX)        ^^
> >> ^^  [log in to unmask]                                          ^^
> >> ^^                                                        ^^
> >> ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>
> --
> Stefano.
>
>
>