Rigol DS6000 Series User Manual page 270

RIGOL
Backspace: press this softkey to delete the characters in the "Option License

Input Area" from the right to the left.
Clear: press this softkey to clear all the characters in the "Option License Input

Area".
Apply: press this softkey and the oscilloscope will activate the corresponding

option using the option license currently input.
13-14
13 System Function Setting
DS6000 User's Guide