<?xml version="1.0" encoding="utf-8"?><mads xmlns="http://www.loc.gov/mads/" xmlns:mods="http://www.loc.gov/mods/v3" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.loc.gov/mads/
mads.xsd"><authority><topic authority="http://AATesaurus.cultura.gencat.cat/aat/getty_en">ontologies</topic></authority><related type="other"><topic>controlled vocabularies</topic></related><related type="broader"><topic>reference sources</topic></related><related type="broader"><topic>vocabulary</topic></related><variant type="other"><topic>ontology</topic></variant> <note xml:lang="en"><![CDATA[ Formal, machine-readable specifications of a conceptual model, in which concepts, properties, relationships, functions, constraints, and axioms are all explicitly defined. Refers to a compilation that is not technically a controlled vocabulary, but that uses one or more controlled vocabularies for a defined domain and expresses the vocabulary in a representative language that has a grammar for using vocabulary terms to express something meaningful. Ontologies generally divide their world into the following areas: individuals, classes, attributes, relations, and events. The grammar of the ontology links these areas together by formal constraints that determine how the vocabulary terms or phrases may be used together. ]]></note></mads>