android_frameworks_base/data/fonts/vendor_fonts.xml

<?xml version="1.0" encoding="utf-8"?>
<!--
    Vendor-provided fallback fonts

    This file can be edited to add references to fonts that are not installed or referenced in the
    default system. The file should then be placed in /vendor/etc/fallback_fonts.xml.

    For example, vendors might want to build configurations for locales that are
    better served by fonts which either handle glyphs not supported in the default fonts or which
    handle these glyphs differently than the default fallback fonts.
    Each entry in this list is a "family", which consists of a list of "files"
    (the filenames for that family). The files objects are
    provided in the order of the styles supported for that family: regular, bold, italic, and
    bold-italic. Only providing one font means that all styles will be rendered with that font.
    Providing two means that these two fonts will render regular and bold fonts (italics will
    be mapped to these two fonts).

    There is also an optional "order" attribute on the Family tag. This specifies the index at
    which that family of fonts should be inserted in the fallback font list, where the
    default fallback fonts on the system (in /system/etc/fallback_fonts.xml) start at index 0.
    If no 'order' attribute is supplied, that family will be inserted either at the end of the
    current fallback list (if no order was supplied for any previous family in this file) or
    after the previous family (if there was an order specified previously). Typically, vendors
    may want to supply an order for the first family that puts this set of fonts at the appropriate
    place in the overall fallback fonts. The order of this list determines which fallback font
    will be used to support any glyphs that are not handled by the default system fonts.

    The sample configuration below is an example of how one might provide two families of fonts
    that get inserted at the first and second (0  and 1) position in the overall fallback fonts.

    See /system/etc/system_fonts.xml and /system/etc/fallback_fonts.xml for more information
    and to understand the order in which the default system fonts are loaded and structured for
    lookup.
-->

<!-- Sample fallback font additions to the default fallback list. These fonts will be added
    to the top two positions of the fallback list, since the first has an order of 0. -->
<!--
<familyset>
    <family order="0">
        <fileset>
            <file>MyFont.ttf</file>
        </fileset>
    </family>
    <family>
        <fileset>
            <file>MyOtherFont.ttf</file>
        </fileset>
    </family>
</familyset>
-->