Understanding Rules Files for Data Load and Dimension Build

An Essbase database contains no data when it is created. Data load rules files are sets of operations that Essbase performs on data from an external data source file as the data is loaded, or copied, into the Essbase database. Dimension build rules files create or modify the dimensions and members in an outline dynamically based on data in an external data source. Rules files are typically associated with a particular database, but you can define rules for use with multiple databases. One rules file can be used for both data loads and dimension builds. Rules files have a .rul extension.

See Rules Files and Working with Rules Files.