was ANSI SQL (1989) compliant and utilized the DOS4GW memory manager. This memory manager was also seen in many DOS games of the era. R:Base 3.1 introduced a multi-user network capability. A version was also rolled out for the Convergent Technologies Operating System operating system, this was apparently a follow-on to Burroughs Technologies Operating System (BTOS). By purchasing license packs, the database gained a multi-user capability in five-user increments. This included a sophisticated (for a DOS application in the day) record-level locking scheme. To work properly, the multi-user database had to be on a file server with all users accessing the database through a network. It was not true client-server because processing occurred in the clients. The configuration file expanded to allow language support and user-defined re-mapping of characters. For example, German characters such as the letter "ö" (o with an umlaut) could be remapped to the string oe. There were character fold tables and sort orders could be adjusted by the user. An "unlimited number of licenses" runtime version was offered, allowing developers to sell applications and include the run-time R:Base engine. Example of an R:Base 3.1 command prompt transaction asking the application to list the structure of a database table of California cities, (CALIFCY): R> LIST CALIFCY # Name Type Index Expression 1 STATE TEXT 2 2 FEATURE TEXT 85 3 FEATURET TEXT 9 4 COUNTY1 TEXT 15 5 FIPSST TEXT 2 6 FIPSCO TEXT 3 7 LATITUDE TEXT 7 8 LONGITUD TEXT 8 9 LAT_DEC TEXT 8 10 LON_DEC TEXT 10 11 SOURCELA TEXT 7 12 SOURCELO TEXT 8 13 SOUR_lat TEXT 8 14 SOUR_lon TEXT 10 15 ELEVATIO TEXT 5 16 FIELD16 TEXT 8 17 MAPNAME TEXT 27 18 LAT1 DOUBLE 19 LON DOUBLE 20 ITEM_NO DOUBLE Current number of rows: 7070 R:BASE 4.x R:Base 4.0 rolled out Intel 80386 support and a newer DOS4GW memory manager. It included a newer file format, replacing the format used with Version 3.1. To support legacy customers, Version 4.0 included a copy of Version 3.1 with a lot of warnings about new file format and features of 4 that were not supported in 3.1. While the documentation claimed 2GB data files were supported, there were data integrity problems with some very large tables over 1 million records. The software was designed to accommodate up to 750 tables and easily handled tables with tens of thousands of records. It was