Rigol MSO8064 User Manual page 146

RIGOL
If you enable Zone A, select CH1 as Source A, and select "Not intersect" as the
condition, the following figure is displayed.
Tip
If you enable both Trigger zone A and Trigger zone B, then perform the "A&&B"
operation, and it will become the final trigger condition.
5-56
Chapter 5 To Trigger the Oscilloscope
MSO8000 User Guide