THE MAINTENANCE OF A GBF CONSISTS OF THREE INTERRELATED MAJOR FUNCTIONS: MANUAL MAINTENANCE (PERIODIC VISUAL SCANNING OF THE COMPUTER FILE AND DATA COMPARISON), AUTOMATED UPDATE CAPABILITIES; AND SYSTEM ENHANCEMENTS (ONGOING SYSTEM DEVELOPMENT AND DESIGN). THE GBF MAINTENANCE FUNCTION IS KEYED TO THE AVAILABILITY AND ACCURACY OF SOURCE DATA USED TO SUPPORT, MODIFY, AND EXPAND THE FILE. IN GBF DATA COLLECTION, ACCURACY, COMPREHENSIVENESS, AND DATA COMPATIBILITY ARE OF UTMOST PRIORITY. POTENTIAL SOURCES FOR GBF DATA INCLUDE THE USER; THE POLICE ORGANIZATION USING THE FILES; LOCAL GOVERNMENT AGENCIES THAT MAY HAVE IMPLEMENTED UNIVERSAL SYSTEMS WITH INFORMATION ON BUILDINGS, TRAFFIC PATTERNS, TAX ASSESSMENTS, OR LICENSES; THE COMMERCE DEPARTMENT AND THE CENSUS BUREAU; AND THE PRIVATE SECTOR, ESPECIALLY FOR INFORMATION ON COMMERCIAL BUIDLINGS AND REAL ESTATE. THE HARTFORD POLICE DEPARTMENT (HPD) OFFERS AN EXAMPLE OF THESE MAINTENANCE AND DATA COLLECTION FUNCTIONS. THE HPD INITIATED ITS GBF PROJECT IN 1973 WITH THREE PHASES: DATA COLLECTION, DATA VERIFICATION AND MAINTENANCE, AND ADDITIONAL MAINTENANCE AND APPLICATIONS. WHAT WAS LEARNED THROUGH THE EXPERIENCE AND WHAT REMAINS TOP PRIORITY IS SYSTEM MAINTENANCE; I.E., ENSURING THE EXISTENCE OF TRANSACTIONS WHICH MAINTAIN THE INTEGRITY, CREDIBILITY, AND RELIABILITY OF THE GEO-BASE FILE. FLOW CHARTS AND TABLES ILLUSTRATE THE FILE STRUCTURE. REQUIREMENTS FOR THE MAINTENANCE FUNCTION ARE LISTED. (MHP)