EAD 2002 SCHEMA
The EAD Schema Working Group (SAA/EADWG) is pleased to announce the
release of the EAD 2002 Schema.
The EAD 2002 Schema is available in two syntaxes: Relax NG Schema
and W3C Schema (XSD).
Both versions of the Schema are available at
*** Comments, questions, and error reports should be sent to the EAD
with the subject line: Schema Comment ***
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The RNG version is the maintenance and therefore authoritative version.
The XSD version
is derived from the RNG using Trang, with minor manual 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
by implementing XML Namespace. As a result, DTD compliant instances
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 has
provided an Alpha XSLT for this conversion. See
transform/dtd2schema.xsl. A parameter
on line 51 allows the user to specify whether the resulting schema
should have RNG or
W3C addressing information.
The following elements and their XLink-specific attributes are impacted
by this change:
dao daogrp daoloc
extptr extptrloc extref extrefloc
ref refloc resource
For example, the following DTD compliant tag:
Must be converted to the following:
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
@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
the Latin script is incorrect. The correct code for the Latin script is
"Latn". The case of
the character matters!!
Attribute validations errors indicate that the attribute value does not
conform to the ruling
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