You want to execute an operation when a sort level changes. For example, you can use the Number operation to count the number of sort levels and display it before each sort level. The procedure refers to Number operations only, since this calculation event does not make sense for the other operation types.
You created a table node and use theData tab to read your internal table.
Calculations atBefore Sorting or After Sorting can be executed only if on the Data tab either Event on Sort Begin or Event on Sort End is marked.
You count the number of sort levels. At the beginning or end of the sort levels you can display the target field as the sort level number. In the footer you can display the total number of sort levels.