fontconfig/conf.d/45-generic.conf

<?xml version="1.0"?>
<!DOCTYPE fontconfig SYSTEM "fonts.dtd">
<fontconfig>
  <its:rules xmlns:its="http://www.w3.org/2005/11/its" version="1.0">
    <its:translateRule translate="no" selector="/fontconfig/*[not(self::description)]"/>
  </its:rules>

  <description>Set substitutions for emoji/math fonts</description>

<!-- Keep in sync with 60-generic.conf -->

<!-- Emoji -->

	<!-- System emoji -->
	<alias binding="same">
		<family>Noto Color Emoji</family> <!-- Google -->
		<default><family>emoji</family></default>
	</alias>
	<alias binding="same">
		<family>Apple Color Emoji</family> <!-- Apple -->
		<default><family>emoji</family></default>
	</alias>
	<alias binding="same">
		<family>Segoe UI Emoji</family> <!-- Microsoft -->
		<default><family>emoji</family></default>
	</alias>
	<alias binding="same">
		<family>Twitter Color Emoji</family> <!-- Twitter -->
		<default><family>emoji</family></default>
	</alias>
	<alias binding="same">
		<family>EmojiOne Mozilla</family> <!-- Mozilla -->
		<default><family>emoji</family></default>
	</alias>
	<!-- Third-party emoji -->
	<alias binding="same">
		<family>Emoji Two</family>
		<default><family>emoji</family></default>
	</alias>
	<alias binding="same">
		<family>JoyPixels</family>
		<default><family>emoji</family></default>
	</alias>
	<alias binding="same">
		<family>Emoji One</family>
		<default><family>emoji</family></default>
	</alias>
	<!-- B&W -->
	<alias binding="same">
		<family>Noto Emoji</family> <!-- Google -->
		<default><family>emoji</family></default>
	</alias>
	<alias binding="same">
		<family>Android Emoji</family> <!-- Google -->
		<default><family>emoji</family></default>
	</alias>

	<!-- Add language for emoji, to match other emoji fonts. -->
	<match>
		<test name="family">
			<string>emoji</string>
		</test>
		<edit name="lang" mode="prepend">
			<string>und-zsye</string>
		</edit>
	</match>

	<match>
		<test name="lang">
			<string>und-zsye</string>
		</test>
		<test qual="all" name="family" compare="not_eq">
			<string>emoji</string>
		</test>

		<!-- Add generic family. -->
		<edit name="family" mode="append" binding="strong">
			<string>emoji</string>
		</edit>
	</match>


<!-- Math -->

	<!-- https://en.wikipedia.org/wiki/Category:Mathematical_OpenType_typefaces -->
	<alias binding="same">
		<family>XITS Math</family> <!-- Khaled Hosny -->
		<default><family>math</family></default>
	</alias>
	<alias binding="same">
		<family>STIX Two Math</family> <!-- AMS -->
		<default><family>math</family></default>
	</alias>
	<alias binding="same">
		<family>Cambria Math</family> <!-- Microsoft -->
		<default><family>math</family></default>
	</alias>
	<alias binding="same">
		<family>Latin Modern Math</family> <!-- TeX -->
		<default><family>math</family></default>
	</alias>
	<alias binding="same">
		<family>Minion Math</family> <!-- Adobe -->
		<default><family>math</family></default>
	</alias>
	<alias binding="same">
		<family>Lucida Math</family> <!-- Adobe -->
		<default><family>math</family></default>
	</alias>
	<alias binding="same">
		<family>Asana Math</family>
		<default><family>math</family></default>
	</alias>

	<!-- Add language for math, to match other math fonts. -->
	<match>
		<test name="family">
			<string>math</string>
		</test>
		<edit name="lang" mode="prepend">
			<string>und-zmth</string>
		</edit>
	</match>

	<match>
		<test name="lang">
			<string>und-zmth</string>
		</test>
		<test qual="all" name="family" compare="not_eq">
			<string>math</string>
		</test>

		<!-- Add generic family -->
		<edit name="family" mode="append" binding="strong">
			<string>math</string>
		</edit>
	</match>


</fontconfig>