To create a dimension build rules file:
Determine whether to use the same rules file for data loads and dimension builds.
See Creating Rules Files.
If necessary, change or set the properties of members and dimensions you are building.
If necessary, set record and field operations to change the members in the data source during loading.
See Using a Rules File to Perform Operations on Records, Fields, and Data.
Set field type information, including field type, field number, and dimension.