A system (100) for providing multiple facility healthcare corporations the ability to assign and maintain shared medical record numbers (43) across multiple entities. The system establishes a parent/child relationship among the entities to share medical record number ranges, formats, and data. A patient record identifier database (102) contains patient records in a searchable unit record file (50) and an identification number file (3). A search processor (105) locates relevant records and a rules processor (104) applies various tests to the returned data in order to assign a medical record number (43, 13) to a single unique unit reference number (2, 5, 11) to a person without duplication or conflict with identifiers used at other entities (4, 9, 190). The reference numbers and their associated medical records are shared among the various entities. The sharing relationships may be altered by authorized users accessing on line file maintenance (312) and programs (311).