In Zebra authorities configuration, when using index_heading the subdivisions are joined with two dashes. You can see this when looking at what is indexed : https://wiki.koha-community.org/wiki/Troubleshooting_Zebra#Which_indexes_are_defined.3F For example : field 250 $a Cinéma $x Films $y France $z 2010 Shows : <z:index name="Subject-topical-heading:w Subject-topical-heading:p Subject-topical-heading:s Heading:w Heading:p Heading:s">Cinéma--Films--France--2010</z:index> And a search "Cinéma Films France 2010" on main heading does not find this record. It comes from https://git.koha-community.org/Koha-community/Koha/src/commit/895fc88605f7381218b38463be17531a06403c1a/etc/zebradb/xsl/koha-indexdefs-to-zebra.xsl#L438 Anyone knows where this comes from and how it is supposed to work ?