Are there plans to have the schema support external entities?
Michele
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Michele Rothenberger
Manuscripts Processor
Special Collections Research Center
Syracuse University Library
222 Waverly Avenue
Syracuse, NY 13244
(315) 443-2697
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>>> [log in to unmask] 9/8/2006 2:07 PM >>>
EAD 2002 BETA SCHEMA
The EAD Schema Working Group (SAA/EADWG) is
pleased to announce the Beta release of the EAD 2002 Schema.
*** The Beta Schema is FOR TESTING PURPOSES ONLY!! ***
The Beta testing period will end Friday, September 22, 2006.
BEFORE TESTING, PLEASE READ THE FOLLOWING CAREFULLY.
Provided there are no errors or issues requiring
major revision, the official version of the
Schema is scheduled to be released Monday, October 3, 2006.
The EAD 2002 Beta Schema is available in two syntaxes: Relax NG Schema (RNG)
and W3C Schema (XSD).
Both versions of the Schema are available at
http://www.loc.gov/ead/eadschema.html
*** Comments, questions, and error reports should be sent to the EAD listserv
with the subject line: Schema Comment ***
Listserv address: [log in to unmask]
The RNG version is the maintenance and therefore
authoritative version. The XSD version
is derived from the RNG using Trang, with minor
manual editing subsequent editing.
***
EAD DTD / SCHEMA RELATIONSHIP
With one exception (XLink elements and
attributes), the EAD Schema is a subset of the
EAD 2002 DTD.
The Xlink compatible elements and attributes in
the DTD have been made compliant
by implementing XML Namespace. As a result, DTD compliant instances containing
ANY of the XLink tags and attributes will not
validate against the Schema. These instances
must be converted into XLink compliant tags and
attributes. The EAD Schema WG will
provide XSLT for this conversion with the release
of the official version of the Schema.
The following elements and their XLink-specific
attributes are impacted by this change:
arc archref
bibref
dao daogrp daoloc
extptr extptrloc extref extrefloc
linkgrp
ptr ptrloc
ref refloc resource
title
For example, the following DTD compliant tag:
<extptr
linktype="simple"
href="myimage.jpg"
show="embed"
actuate="onload"/>
Must be converted to the following:
<extptr
xlink:type="simple"
xlink:href="myimage.jpg"
xlink:show="embed"
xlink:actuate="onLoad"/>
Do note also that while RNG does support external
entities, XSD does not. Thus @entityref
must be resolved and converted to @xlink:href on
XLink "locator" tags. Do note also that
@xlink:href is a required attribute on XLink
"locator" tags, and thus using RNG will require
the presence of this attribute on the relevant tags.
With the exception of the XLink tags and
attributes, a Schema valid instance will be a DTD
valid instance. However, because of the
imposition of datatype contraints on specific
attribute values, a DTD valid instance may not be Schema valid.
The following attributes are impacted by the
imposition of datatype constraints:
@normal on <unitdate> and <date>: constrained
to date and date range subset of ISO 8601
@repositorycode: constrained to ISO 15511 (ISIL)
@mainagencycode: constrained to ISO 15511 (ISIL)
@langcode: constrained to ISO 639-2 alpha-3 code list
@scriptcode: constrained to ISO 15924 code list
@countrycode: constrained to ISO 3166-1 alpha-2 code list
In preliminary testing, many of the attribute
values intended by encoders to be compliant
with each relevant ISO standard were found to be
incorrect. Thus scriptcode="latn" for
the Latin script is incorrect. The correct code
for the Latin script is "Latn". The case of
the character matters!!
The ISO 8601 rules for dates are particular
challenging, and testing found that errors were
common.
Nevertheless, this is a Beta version of the
Schema. The constraints for the attribute values
are enforced using either controlled vocabulary
lists or regular expressions. The regular
expressions are the Schema editor's
interpretation of the ISO constraints, and thus may be
in error. They are also susceptible to typographical error.
When attribute validations errors are
encountered, they may be because the attribute value
does not conform to the ruling ISO standard, or
the Schema has incorrectly interpreted the
standard or the Schema simply contains a typographical error.
Please evaluate attribute value errors and report
only those errors that appear to be Schema
errors. If in doubt, report the error to the EAD listserv.
***
Publisher: Society of American Archivists and the Library of Congress
Funding: National Historical Publications and Records Commission
Editors (SAA/EADWG/EAD Schema Working Group):
Francoise Bourdon (Bibliothèque nationale de France)
Terry Catapano (Columbia University)
Jerry McDonough (University of Illinois)
Lee Mandell (New York University)
Chris Prom (University of Illinois)
Stephen Yearl (Yale University)
Daniel Pitti (University of Virginia), Chair
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