[Koha] Migrating data from ABCD to Koha

Hi There is an institution in Zimbabwe that have been using ABCD but are having challenges with the system. They are now contemplating going the koha root. However, they want their bibliographic records to be migrated to Koha. They are saying they are not using MARC format in their ABCD. Any idea on how to do the migration. Regards, Admire Mutsikiwa