In the "class" field you can enter a classname for each player (classnames could be anything, like M, 1, 2, 3, 4 5, JUN, SEN etc). It will then be possible to get the standings listed by class. Activate this in the window Tournament Options.
Please note: the calss field is NOT neccessarily the same as the player's Grand-prix class.
In the "GP" field you can enter the Grand Prix class to which each player is assigned. Usually this is formally assigned by the relevant grand prix organisers, the local federation or similar If supported by your local federation's file format, this field will be filled in automatically when you pick a player from the rating list.
The GP field is not normally visible in the main window until you select this under "options".