The Custom Index builder can alter the target dictionary by adding nodes. This is done to support nodes that exist in the source dictionary and that contain performance data, but they do not exist in the target dictionary prior to the entity build. Nodes added to the target dictionary by the Custom Index builder have an UPDATE_SOURCE of CUST.
All levels must exist in the target dictionary, that is, in the source dictionary prior to the entity build. Nodes are added, if needed, by the Custom Index builder.
Also, to ensure a proper entity build, the target and source dictionary levels must be aligned.
Below are sample structures of the Custom Index builder to show the proper target and source dictionary alignment as well as the nodes that are added to the target dictionary from the source dictionary.