This scrambling program is no longer used and only kept for legacy purposes.
The current official scrambling program can be found here
D means all layers below the U face together in one move.
R means all layers right from the L face together in one move.
++ means 2/5 move clockwise (144 degrees), -- means 2/5 move counterclockwise (-144 degrees).
U is the regular move of the U face, according to standard cube notation.
Program by Clément Gallet, based on earlier work by Jaap Scherphuis. Idea by Stefan Pochmann.