<?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">photochromism</topic></authority><related type="broader"><topic>photosensitivity</topic></related><variant type="other"><topic>photochromic</topic></variant> <note xml:lang="en"><![CDATA[ Describes a phenomenon of photosensitivity in which a material undergoes a change of color when illuminated with light of the appropriate wavelength; and reverts to its original state either in the dark or upon treatment with irradiation of a different wavelength.  ]]></note></mads>