21c Analytic View Aggregation Table Support

Hello!

Could somebody please advise on proper syntax for Analytic View (AV) Aggregation Table Support in 21c? According to 21c DWH Guide:

When creating an analytic view, you can specify an object, such as an aggregate table, a view, or a materialized view, to use in a level grouping cache in place of a materialized view. You can then refresh the aggregate table as desired, which allows you complete control of the aggregate results.

You specify the aggregation object with the MATERIALIZED USING keywords for a level in the measure group of the cache specification clause of the analytic view.