Instance for ALV Grid Control 
This instance is defined with reference to class cl_gui_alv_grid:
Syntax
data <name of reference variable> type ref to cl_gui_alv_grid.
An instance for the ALV Grid Control manages all information in a list on your Dynpro. You can call methods on this instance and use them to define and change properties of this control.
Caution
Do not derive this class in order to access protected areas of the class. This is not necessary for using the ALV Grid Control.

Class cl_gui_alv_grid contains both control-specific methods and methods of the Control Framework.