/usr/share/xml/ is in docbook5-xml 5.0-2.
This file is owned by root:root, with mode 0o755.
..
/usr/share/xml/docbook/
/usr/share/xml/docbook/schema/
/usr/share/xml/docbook/schema/catalog-docbook5.xml
/usr/share/xml/docbook/schema/dtd/
/usr/share/xml/docbook/schema/dtd/5.0/
/usr/share/xml/docbook/schema/dtd/5.0/docbook.dtd
/usr/share/xml/docbook/schema/rng/
/usr/share/xml/docbook/schema/rng/5.0/
/usr/share/xml/docbook/schema/rng/5.0/docbook.rnc
/usr/share/xml/docbook/schema/rng/5.0/docbook.rng
/usr/share/xml/docbook/schema/rng/5.0/docbookxi.rnc
/usr/share/xml/docbook/schema/rng/5.0/docbookxi.rng
/usr/share/xml/docbook/schema/schematron/
/usr/share/xml/docbook/schema/schematron/5.0/
/usr/share/xml/docbook/schema/schematron/5.0/docbook.sch
/usr/share/xml/docbook/schema/xsd/
/usr/share/xml/docbook/schema/xsd/5.0/
/usr/share/xml/docbook/schema/xsd/5.0/docbook.xsd
/usr/share/xml/docbook/schema/xsd/5.0/xlink.xsd
/usr/share/xml/docbook/schema/xsd/5.0/xml.xsd
/usr/share/xml/docbook/stylesheet/
/usr/share/xml/docbook/stylesheet/docbook5/
/usr/share/xml/docbook/stylesheet/docbook5/db4-upgrade.xsl