/usr/share/xml/docbook/ is in docbook-simple 1.1-4.2.
This file is owned by root:root, with mode 0o755.
..
/usr/share/xml/docbook/custom/
/usr/share/xml/docbook/custom/simple/
/usr/share/xml/docbook/custom/simple/1.0/
/usr/share/xml/docbook/custom/simple/1.0/catalog
/usr/share/xml/docbook/custom/simple/1.0/catalog.xml
/usr/share/xml/docbook/custom/simple/1.0/css/
/usr/share/xml/docbook/custom/simple/1.0/css/sdocbook.css
/usr/share/xml/docbook/custom/simple/1.0/sdbcent.mod
/usr/share/xml/docbook/custom/simple/1.0/sdbhier.mod
/usr/share/xml/docbook/custom/simple/1.0/sdbpool.mod
/usr/share/xml/docbook/custom/simple/1.0/sdocbook-custom.dtd
/usr/share/xml/docbook/custom/simple/1.0/sdocbook.dtd
/usr/share/xml/docbook/custom/simple/1.0/sdocbookref-custom.dtd
/usr/share/xml/docbook/custom/simple/1.0/sdocbookref.dtd
/usr/share/xml/docbook/custom/simple/1.0/sinclist.mod
/usr/share/xml/docbook/custom/simple/1.1/
/usr/share/xml/docbook/custom/simple/1.1/catalog
/usr/share/xml/docbook/custom/simple/1.1/catalog.xml
/usr/share/xml/docbook/custom/simple/1.1/css/
/usr/share/xml/docbook/custom/simple/1.1/css/sdocbook.css
/usr/share/xml/docbook/custom/simple/1.1/sdbcent.mod
/usr/share/xml/docbook/custom/simple/1.1/sdbhier.mod
/usr/share/xml/docbook/custom/simple/1.1/sdbpool.mod
/usr/share/xml/docbook/custom/simple/1.1/sdocbook-custom.dtd
/usr/share/xml/docbook/custom/simple/1.1/sdocbook.dtd
/usr/share/xml/docbook/custom/simple/1.1/sdocbookref-custom.dtd
/usr/share/xml/docbook/custom/simple/1.1/sdocbookref.dtd
/usr/share/xml/docbook/custom/simple/1.1/sinclist.mod