When you build your data warehouse, tables may end up containing fields which you do not want to appear in your reporting and visualization tools.
This issue sometimes pops up in dimensional modeling when strictly abiding to the Kimball guidelines. Fact tables should only contain surrogate keys, measures, and degenerate dimensions. Surrogate keys are calculated for every dimension table and this usually happens in the staging database. In some cases, however, the surrogate keys need to be looked up at the data warehouse level.
You would then need to bring the natural keys to the data warehouse to perform the surrogate key lookup but don’t have any way of getting rid of the natural keys. Instead the number of columns on the fact table increases, as does the number of physical disc reads required when dealing with very large fact tables.
In Jet Data Manager versions prior to v2017, this can be accomplished by creating a new table and copying all the useful fields from the old table.
In Jet Data Manager 2017, you have the option to mark a field as raw-only.
A raw-only field is not copied from the "raw" to the "valid" instance of the table. Instead it is purged from the table and will not show up in OLAP cubes or any presentation tools that read directly from the data warehouse.