Zebra search index was added in Bug 6499. Need to modify ./koha-tmpl/opac-tmpl/bootstrap/en/modules/opac-advsearch.tt ./koha-tmpl/opac-tmpl/prog/en/modules/opac-advsearch.tt ./koha-tmpl/intranet-tmpl/prog/en/modules/catalogue/advsearch.tt In order to add 'OCLC Number' as an option in advanced search in the OPAC and staff client.
Don't need to update ./koha-tmpl/opac-tmpl/prog/en/modules/opac-advsearch.tt
See discussion for naming on bug 6499.