Inherited Sources
An inherited source is a logical table that inherits the definition of an existing dimension or measure table in the same space without having to replicate the physical data structure. An inherited source is not an actual data source but a pointer to another data source.
For example, you could have a source called Owner that contains the column Owner ID. However you may want to do reporting by Last Modified by Owner and Created by Owner. Instead of cloning the Owner source and creating two new data sources, you could create two new inherited sources for Last Modified by Owner and Created by Owner and inherit the columns from the Owner source. This results in three folders in the default subject area: Owner, Created by Owner, and Last Modified by Owner. This allows you to then create a report against any of the three.