/usr/share/xindy/tex/ is in xindy-rules 2.5.1.20160104-4build1.
This file is owned by root:root, with mode 0o755.
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/usr/share/xindy/tex/inputenc/
/usr/share/xindy/tex/inputenc/cp1250.xdy
/usr/share/xindy/tex/inputenc/cp1251.xdy
/usr/share/xindy/tex/inputenc/cp1252.xdy
/usr/share/xindy/tex/inputenc/cp437.xdy
/usr/share/xindy/tex/inputenc/cp850.xdy
/usr/share/xindy/tex/inputenc/cp855.xdy
/usr/share/xindy/tex/inputenc/cp866.xdy
/usr/share/xindy/tex/inputenc/iso88595.xdy
/usr/share/xindy/tex/inputenc/isoir111.xdy
/usr/share/xindy/tex/inputenc/koi8-r.xdy
/usr/share/xindy/tex/inputenc/koi8-u.xdy
/usr/share/xindy/tex/inputenc/latin.xdy
/usr/share/xindy/tex/inputenc/latin1.xdy
/usr/share/xindy/tex/inputenc/latin2.xdy
/usr/share/xindy/tex/inputenc/latin3.xdy
/usr/share/xindy/tex/inputenc/utf8.xdy