The first column is the group index, the second column is the report event which created this line. All other columns contain the contents of the datarow.
-1, report-header, column1 , column2, ... 0, group-header, column1 , column2, ... 0, itemband, column1 , column2, ... .. .. .. 0, group-footer, column1 , column2, ... -1, report-footer, column1 , column2, ...