The selection screen that you define when you use the PARAMETERS or SELECT-OPTIONS statements on their own, has a standard layout in which all parameters appear line by line. This layout is not always sufficient. For example, when you define a group of radio buttons, you should set off these buttons against other input fields so that the user can identify them as a group.
The SELECTION-SCREEN statement has its own formatting options that you can use to define the layout for selection screens. You can define the layout of parameters and selection criteria and display comments and underlines on the selection screen.