Sustainability of Digital Formats: Planning for Library of Congress Collections

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Digital Formats Descriptions as XML

The digital format descriptions presented at this Web site are known as "fdds" or format description documents. These were initially developed under the auspices of the Library of Congress National Digital Information Infrastructure and Preservation Program (NDIIPP). The first descriptions were drafted as static HTML files in 2003, with updates and additions continuing in the years that followed. The production process began to move into an XML mode in late 2007. By 2012 all of the existing descriptions had been converted to XML and new descriptions were being created in XML. The production of format descriptions is now managed within the Library Services unit of the Library of Congress.

The HTML versions on the Web site are produced via an XSLT transformation, and they carry this explanatory comment: <!--This HTML FDD was generated using an XSLT transformation from an XML master FDD, based on version 1.1 of the FDD schema.-->.

XML Schema for Format Descriptions
The format description documents comply with a primary XML Schema Definition (.xsd file), which refers to a subsidiary schema using an xsd:include declaration. The subsidiary schema handles HTML styling within the longer text fields in FDDs.

Version 1.2, January 26, 2022.

The only changes between versions 1.2 and 1.1 were to add the Quality and Functionality factors for the new Aggregate content category. These changes will not invalidate existing FDDs available on this site. As FDDs are updated, they will refer to version 1.2 of the schema.

Version 1.1, November 11, 2016.

The only changes between version 1.1 and 1.0 were to the enumerated lists in the schema: (a) adding a few signifier types including Pronom PUID and a generic FOURCC type and (b) adding application domains for email and cad/cam.

Previous version: 1.0, July 20, 2012.

XML Format Description Documents
The XML descriptions may be downloaded as a group, packaged in a ZIP file. A fresh file is made after every addition to the site, and it may be downloaded from this location:

XML descriptions may also be accessed individually if the identifier is known, using the following path- and file-name pattern: // Here's an example. The HTML version of the main PDF description is here:

The corresponding XML version is here:

Last Updated: 06/30/2023