Describes the changes of the Bibliographic Information System of the Economic Commission for Latin America and the Caribbean (ECLAC) from its 1983 version to the last 2003 version. The 1983 and 1993 releases were created for CDS/ISIS software for MS-DOS (MicroISIS). The 2003 version of the ECLAC Format was created for use in Windows environment (Winisis). The ECLAC Format in his 1983 version has 82 fields, 63 fields in 1993 and in the 2003 version 50 fields. The last version includes a new field (tag 100) which allows enter the Uniform Resource Locator (URL) for electronic resources. A comparative table of the 1984, 1993 and 2003 versions of the Field Definition Table (FDT) is included. This poster session will be very helpful to librarians and ISIS users thinking of migrating dat
abases, addresing issues as the main changes in the system, relationship with Anglo-American Cataloguing Rules (AACR2) and individual cases of information entry.