The Metadata Authority Description Schema (MADS) is a hierarchical XML-based bibliographic description schema created by the Library of Congress’ Network Development and MARC Standards Office. MADS serves as a companion to the Metadata Object Description Schema (MODS) to provide metadata about the authoritative entities used in MODS descriptions.
The MADS schema sheets and official documentation can be found at the official LOC MADS page.
XML Path Language (XPath) is a query language employed by the XML forms in the repository to both write the proper nodes to the MADS XML datastream and read the nodes from that datastream t to display in the form.
How XPath Syntax and XML match up (color coded):
XPath Syntax noted in metadata mapping sheets and employed in XML forms
mads:authority/mads:name[@type="corporate"]/mads:namePart
Resulting XML in MADS datastream
<mads xmlns="http://www.loc.gov/mads/v2" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:mads="http://www.loc.gov/mads/v2">
<authority>
<name type="corporate">
<namePart>Archive of the Indigenous Languages of Latin America</namePart>
</name>
</authority>