Two or more data items in a COBOL record that contain identical information but that have been identified to Relativity as sets of redundant data items. Redundant data items include situations such as where one data item is identical to the first characters of another data item. One place where redundant data items are defined is in keys, where different keys provide different look-up capabilities in a file. Using Relativity, an item set becomes one data item in a relational table.