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Greetings,

At the recent meeting of the METS editorial board, two deficiencies with
the current (v.1.0 zeta) METS schema were identified:

1. As Robin Wendler noted in a recent post, people working with large,
multi-track
audio files face a significant problem with regards to the current schema's
structural map section.  Typically, they will have one byte stream per track,
where each byte stream is so large (for master files) that they cannot be
contained in a single file on the file system (each  byte stream exceeds the
operating system's limits for maximum file size).  While
the v1.0 schema has the <par> element within the structMap to allow you to
indicate
that multiple files should be played in parallel, it is inadequate in those
cases where
a single byte stream must be placed in more than one file.  To rectify
this, the board
is proposing that the schema be modified to allow the <seq> element to
appear as
a subelement of <par>.  This would allow those encoding structural metadata to
group a series of files together as a single bytestream to be played in
parallel
with another series of files, e.g.,

         <par>
                 <seq>
                         <area FILEID="tract1part1"/>
                         <area FILEID="tract1part2"/>
                 </seq>
                 <seq>
                         <area FILEID="tract2part1"/>
                         <area FILEID="tract2part2"/>
                 </seq>
         <par>

2. There have been numerous questions on the list over the past year as to how
to record the hyperlink structure of a website within a METS document.  To
date,
METS has made no provision for recording such information.  While it could
record
the hierarchical tree structure of a website, recording the links between
the nodes of
that tree was impossible.  To rectify this, the editorial board is
proposing the addition
of a new, major section to the METS schema, <structLink>.  <structLink> allows
you to encode one or more <smLink> elements, where each <smLink> records a
hypertext link between two nodes in the <structMap> section of a METS document
using the 'to' and 'from' attributes.  Note that to record these links your
<structMap>
will have to contain at least a <div> for the origin and target of each
link.  That is, if you have
an HTML page with 3 links to other pages, you'd probably want something like
the following in your <structMap>

         <div ID="p1" LABEL="page1">
                 <div ID="p1L1" LABEL="link1">
                 <div ID="p1L2" LABEL="link2">
                 <div ID="p1L3" LABEL="link3">
         </div>
         <div ID="p2" LABEL="page2"/>
         <div ID="p3" LABEL="page3"/>
         <div ID="p4" LABEL="page4"/>

and then the following in <structLink>

         <smLink to="p2" from="p1L1"/>
         <smLink to="p3" from="p1L2"/>
         <smLink to="p4" from="p1L3"/>

[NB: these examples are highly abbreviated to clarify the use of the new
features.  Also note that you are not restricted to linking between <div>
elements
in the structMap.  If you have an image map in a web page, for example, it
would make more sense to use <area> elements to indicate the various parts
of the image map, and then use those <area> elements as the 'from' parts of
an <smLink>.]

A revised version of the METS schema incorporating these proposed changes
is now available at the METS website at:

         http://www.loc.gov/standards/mets/mets.v1-1.xsd

The changes have been made in such a way to ensure backwards compatibility
with existing METS documents.  If your METS document validated against
the v.1.0 schema, it should also validate against the new proposed schema.

We will be taking comments on the proposed schema for 2 weeks (until June 17).
All comments should be posted to the METS listserv ([log in to unmask]).  If no
objections
are raised, the proposed version will become the official new version of
METS after this
two week review period is complete.  If there are problems identified with
the proposal,
the editorial board will try to address them.

Thanks!  We look forward to hearing from you.



Jerome McDonough
Digital Library Development Team Leader
Elmer Bobst Library, New York University
70 Washington Square South, 8th Floor
New York, NY 10012
[log in to unmask]
(212) 998-2425