Understanding MADS: The XML Authority Data Schema

The Metadata Authority Description Schema (MADS) is an XML-based standard developed by the Library of Congress to represent metadata authority records in a web-compatible, structured format. Designed as an authority companion to the Metadata Object Description Schema (MODS), MADS provides a simplified subset of MARC 21 Authority elements formatted into structured XML. This article details what MADS is, its core XML elements, how it organizes authorized headings and relationships, and how it structures authority data for digital repositories.

What is MADS?

MADS is a descriptive XML standard designed to define and control metadata entities such as individuals, corporate organizations, geographic locations, subjects, and uniform titles. While traditional library systems rely on complex MARC 21 Authority formats, MADS delivers a more accessible, human-readable, and machine-actionable XML structure.

MADS is frequently used in digital libraries, repositories, and archives to ensure consistency across descriptive metadata fields by standardizing authorized names, concepts, and relationships.

Core Structural Elements in MADS XML

A MADS record is encapsulated within a <mads> root element (or within <madsCollection> when bundling multiple records). The schema structures authority data primarily by dividing it into preferred headings, alternative terms, related entities, and contextual metadata.

1. Authorized Heading (<authority>)

The <authority> element contains the authorized, preferred form of a name, title, or concept. Every MADS record must contain exactly one <authority> tag.

Within <authority>, specific entity descriptors are declared: * <name>: Designates personal, corporate, or conference names. Includes sub-elements like <namePart> and attributes like type="personal". * <titleInfo>: Represents uniform titles or series. * <topic>: Defines topical subject terms. * <geographic>: Represents geographic locations. * <temporal>: Defines standardized chronological or time periods. * <genre>: Indicates style, format, or genre classifications.

2. Variant Headings (<variant>)

The <variant> element represents non-preferred or alternative forms of the heading (equivalent to “See from” or 4XX fields in MARC Authority records). It uses the same entity sub-elements as the <authority> tag (<name>, <topic>, etc.) to capture misspellings, pseudonyms, maiden names, or alternative phrasings.

The type attribute on <variant> can specify the relationship type, such as type="other".

The <related> element captures connections to other authorized headings (equivalent to “See also” or 5XX fields in MARC). It defines associative or hierarchical relationships between entities.

The type attribute defines the nature of the relationship, including: * type="broader": A broader term in a taxonomy. * type="narrower": A narrower term or sub-concept. * type="other": A general associative connection (e.g., related organizations).

4. Descriptive and Contextual Elements

MADS includes supplementary elements that provide historical or biographical context to disambiguate entities: * <note>: General notes, biographical sketches, or historical data. * <affiliation>: Institutions or organizations associated with a person. * <fieldOfActivity>: Professional fields or areas of expertise. * <identifier>: Standard identifiers (such as ISNI, ORCID, or LCNAF IDs). * <url>: Web links related to the entity. * <recordInfo>: Administrative metadata about the record itself, including creation date, source cataloging agency, and change history.

Example of a MADS XML Record

Below is an example of a MADS XML record defining an author with an authorized name, a variant name, and an external identifier:

<?xml version="1.0" encoding="UTF-8"?>
<mads xmlns="http://www.loc.gov/mads/v2" 
      xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
      xsi:schemaLocation="http://www.loc.gov/mads/v2 http://www.loc.gov/standards/mads/mads-2-0.xsd">
  
  <!-- Authorized Heading -->
  <authority>
    <name type="personal">
      <namePart type="family">Twain</namePart>
      <namePart type="given">Mark</namePart>
      <namePart type="date">1835-1910</namePart>
    </name>
  </authority>

  <!-- Variant Form / Pseudonym Mapping -->
  <variant type="other">
    <name type="personal">
      <namePart type="family">Clemens</namePart>
      <namePart type="given">Samuel Langhorne</namePart>
      <namePart type="date">1835-1910</namePart>
    </name>
  </variant>

  <!-- Context and Identifiers -->
  <fieldOfActivity>Literature</fieldOfActivity>
  <note type="biography">American writer, humorist, and lecturer.</note>
  <identifier type="viaf">50566653</identifier>
  
  <!-- Record Administration -->
  <recordInfo>
    <recordOrigin>Converted from MARC Authority record.</recordOrigin>
    <recordCreationDate encoding="iso8601">2023-01-15</recordCreationDate>
  </recordInfo>

</mads>

Benefits of Structuring Authority Data with MADS