Encoded Archival Description
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Encoded Archival Description (EAD) is an XML standard for encoding archival finding aids, maintained by the Technical Subcommittee for Encoded Archival Description of the Society of American Archivists, in partnership with the Library of Congress.
EAD originated in 1993, at the University of California, Berkeley. The project's goal was to create a data standard for describing archives, similar to the MARC standards for describing bibliographic materials. Such a standard enables archives, museums, libraries, and manuscript repositories to list and describe their holdings in a manner that would be machine-readable and therefore easy to search, maintain, exchange. Since its inception, many archives and special collections have adopted it.
In addition to the development and maintenance work done by the Society of American Archivists and the Library of Congress, the Research Libraries Group (RLG) has developed and published a set of "Best Practice" implementation guidelines for EAD, which lays out mandatory, recommended, and optional elements and attributes. RLG has also provided a kind of clearinghouse for finding aids in EAD format, known as ArchiveGrid. Member libraries provide RLG the URL for their finding aids; RLG automatically harvests data from the finding aids, indexes it, and provides a search interface for the index, thus giving researchers the ability to search across several hundred institutions' collections with a single query. RLG also has developed the "RLG Report Card," an automated quality-checking program that will analyze an EAD instance and report any areas where it diverges from the best practices guidelines.
The EAD standard is currently (2013) undergoing revision.
A number of repositories in the United States, Canada, the United Kingdom, France, Australia and elsewhere have adopted and implemented EAD with varying levels of technical sophistication. One of the most ambitious efforts is the Online Archive of California, a union catalog of over 5000 EAD finding aids covering manuscripts and images from institutions across the state. The French National Library Francois Mitterrand publishes more than 90000 EAD finding aids covering archives and manuscripts.
EAD DTD 
The EAD standard's document type definition (DTD) specifies the elements to be used to describe a manuscript collection as well as the arrangement of those elements (for example, which elements are required, or which are permitted inside which other elements). EAD 1.0 was an SGML DTD; EAD 2002, the second and current incarnation of EAD, was finalized in December 2002 and is an XML DTD. The EAD tag set has 146 elements and is used both to describe a collection as a whole, and also to encode a detailed multi-level inventory of the collection. Many EAD elements have been, or can be, mapped to content standards (such as DACS and ISAD(G)) and other structural standards (such as MARC or Dublin Core), increasing the flexibility and interoperability of the data.
Parts of an EAD finding aid 
The first section of an EAD-encoded finding aid is the
eadheader. This section contains the
title and optional
subtitle of the collection and detailed information about the finding aid itself: who created it, when it was created, its revision history, the language the finding aid is written in, and so on. The
eadheader itself has a number of required attributes that map to various ISO standards such as ISO 3166-1 for country codes and ISO 8601 for date formats.
eadheader and its child elements can be mapped to other standards for easy interchange of information. They are often mapped to Dublin Core elements such as Creator, Author, Language. For example, in the excerpt below the
relatedencoding="DC" attribute of the
eadheader element specifies that child elements will be mapped to Dublin Core; the child element
<author encodinganalog="Creator"> indicates that the EAD element
<author> maps to the Dublin Core element
Example of an eadheader:
<eadheader audience="internal" countryencoding="iso3166-1" dateencoding="iso8601" langencoding="iso639-2b" relatedencoding="DC" repositoryencoding="iso15511" scriptencoding="iso15924"> <eadid countrycode="us" identifier="bachrach_lf" mainagencycode="NSyU">bachrach_lf</eadid> <filedesc> <titlestmt> <titleproper encodinganalog="Title">Louis Fabian Bachrach Papers</titleproper> <subtitle>An inventory of his papers at Blank University</subtitle> <author encodinganalog="Creator">Mary Smith</author> </titlestmt> <publicationstmt> <publisher encodinganalog="Publisher">Blank University</publisher> <date encodinganalog="Date" normal="1981">1981</date> </publicationstmt> </filedesc> <profiledesc> <creation>John Jones <date normal="2006-09-13">13 Sep 2006</date> </creation> <langusage> <language encodinganalog="Language" langcode="eng">English</language> </langusage> </profiledesc> </eadheader>
archdesc section contains the description of the collection material itself. First, the Descriptive Identification or
did element contains a description of the collection as a whole, including the creator (which may be an individual or an organization), size (usually given in linear feet), inclusive dates, language(s), and an abstract or brief description. As with the
eadheader above, elements may be mapped to correspondeing standards; elements in this section are usually mapped to MARC elements. For example, in the excerpt below the
relatedencoding="MARC21" attribute of the
archdesc element specifies that child elements will be mapped to MARC21; the child element
<unittitle encodinganalog="245$a" label="Title: "> indicates that the
unittitle element maps to MARC field 245, subfield a.
<archdesc level="collection" type="inventory" relatedencoding="MARC21"> <did> <head>Overview of the Collection</head> <repository encodinganalog="852$a" label="Repository: ">Blank University</repository> <origination label="Creator: "> <persname encodinganalog="100">Brightman, Samuel C. (Samuel Charles), 1911-1992</persname> </origination> <unittitle encodinganalog="245$a" label="Title: ">Samuel C. Brightman Papers</unittitle> <unitdate encodinganalog="245$f" normal="1932/1992" type="inclusive" label="Inclusive Dates: ">1932-1992</unitdate> <physdesc encodinganalog="300$a" label="Quantity: "> <extent>6 linear ft.</extent> </physdesc> <abstract encodinganalog="520$a" label="Abstract: "> Papers of the American journalist including some war correspondence, political and political humor writings, and adult education material </abstract> <unitid encodinganalog="099" label="Identification: " countrycode="us" repositorycode="NSyU">2458163</unitid> <langmaterial label="Language: " encodinganalog="546"> <language langcode="eng">English</language> </langmaterial> </did>
Several additional descriptive elements may follow the
bioghist- biographic description of the person or organization
scopecontent- a detailed narrative description of the collection material
relatedmaterial- description of items which the repository acquired separately but which are related to this collection, and which a researcher might want to be aware of
separatedmaterial- items which the repository acquired as part of this collection but which have been separated from it, perhaps for special treatment, storage needs, or cataloging
controlaccess- a list of subject headings or keywords for the collection, usually drawn from an authoritative source such as Library of Congress Subject Headings or the Art and Architecture Thesaurus
userestrict- statement concerning any restrictions on the material in the collection
The second, and usually largest, section of the
archdesc is the
dsc, which contains a full inventory of the collection broken down into progressively smaller intellectual chunks. EAD offers two options: the
c element which can be nested within itself to an unlimited level, and a set of numbered container elements
c12 which can only be nested numerically (i.e. a
c01 can contain only a
c02 can contain only a
c03, and so on). Note that the
c0# elements refer to intellectual subdivisions of the material; the actual physical container is specified using the
container element. The inventory may go down to as detailed a level as desired. The example below shows an inventory to the folder level.
Example of an inventory:
<dsc type="combined"><head>Inventory</head> <c01> <did> <unittitle>Correspondence</unittitle> </did> <c02> <did> <unittitle>Adams, Martha</unittitle> <unitdate normal="1962/1967">1962-1967</unitdate> <container type="box">1</container> <container type="folder">1</container> </did> </c02> <c02> <did> <unittitle>Barnett, Richard</unittitle> <unitdate normal="1965">1965</unitdate> <container type="box">1</container> <container type="folder">2</container> </did> </c02> ...etc </c01> <c01> <did> <unittitle>Writings</unittitle> </did> <c02> <did> <unittitle>Short stories</unittitle> <unitdate normal="1959/1979">1959-1979</unitdate> <container type="box">5</container> <container type="folder">1-9</container> </did> </c02> </c01> </dsc>
See also 
- "Development of the Encoded Archival Description DTD".
- , RLG Best Practice Guidelines for Encoded Archival Description, 2002.
- , RLG EAD Report Card.
- "EAD Revision Under Way," Library of Congress, http://www.loc.gov/ead/eadrevision.html
- EAD Version 2002 official home page
- SAA EAD Roundtable
- ICA-AtoM open source archival description software
- PLEADE open source archival publishing software
- Online Archive of California
- RLG Best Practices Guidelines for Encoded Archival Description
- RLG EAD Report Card
- Society of American Archivists
- Archivist's Toolkit
- Calames, French universities archives and manuscripts catalog
- AOMS, French archives catalog of CNRS labs
- Archives Hub, a gateway to thousands of the UK’s richest archives