Hello Gerhard,
thanks for clarification. Now I got your problem.
From my point of view this is not a requirement which has to be solved directly by the model itself, but from the consumer. Only the consumer knows over which attributes the aggregation should be done for e.g. the "sum" line.
In the context of AdHoc reporting using information views you will have a consumer tool. For example Analysis for Office or Lumira out of the BO Universe. I do not think that a business end user will directly use the information view itself. With Analysis for Office you consume the Attributes and Measures you wanna have and define if for example an additional aggregated line should be displayed.
Best Regards,
Florian