These two fields allow to specify a different default assignee for ticket opened against this package in bugzilla. Note: The EPEL field is always displayed for packages in the 'rpms' namespace regardless of whether it is used in bugzilla or not.
You have to install one of mogstored-backend-* and to edit /etc/sysconf/mogstored to match HTTP server of your choice if you are not satisfied with built-in DAV (mogstored-backend-none).