Grigoy,

I have not been able to figure out a way to do this but I have reached out to some more clever people to see if they can.  It certainly is not a OOTB feature.

Sincerely,

Cecil Howell, CSA |  Senior Instructor  |  Pegasystems Inc.

So this is actually pretty simple to accomplish for LIST reports.

1) Create a custom control that outputs the page list subscript of the current page:

         <span><%=tools.getActive().getParentProperty().indexOf()%></span>

2) Add a column to the report (should be first column) and assign it to any property you want

3) Change the column to be formatted using the custom control you just created

Now when the report is run the custom control will output the row number.

Regards

Emilio Gaudette