The range of <offset> is related to the current mode of the horizontal 
timebase (refer to :TIMebase:MODE) and run state of the oscilloscope. 
―  YT mode 
RUN: (-0.5 x MemDepth/SampleRate) to 1s (when the horizontal 
timebase is less than 200ms/div) 
(-0.5 x MemDepth/SampleRate) to (10 x MainScale) (when the 
horizontal timebase is greater than or equal to 200ms/div, namely 
the "Slow Sweep" mode) 
STOP: (-MemDepth/SampleRate) to (1s + 0.5 x MemDepth/SampleRate) 
―  Roll mode 
RUN: This command is invalid. 
STOP: (-12 x MainScale) to 0 
Wherein, MemDepth is the current memory depth of the oscilloscope, 
SampleRate is the current sample rate of the oscilloscope, and MainScale is the 
current main timebase scale of the oscilloscope. 
  When the horizontal timebase mode is YT and the horizontal timebase is 
200ms/div or larger (namely the "Slow Sweep" mode), this command is invalid 
when the oscilloscope is in the transition to the "Stop" state. 
:TIMebase:MAIN:OFFSet 0.0002 /*Set the main timebase offset to 20ms*/ 
:TIMebase:MAIN:OFFSet?                  /*The query returns 2.0000000e-04*/