Agilent Technologies ESA Series User's/Programmer's Reference page 311

Selects auto or manual mode for video bandwidth to resolution bandwidth ratio.
Refer to Figure 2-3 on page
RBW Ratio auto rules.
Factory Preset
and *RST: On
History: Added with firmware revision A.08.00.
Front Panel
Access: BW/Avg, VBW/RBW, Auto Man
Chapter 5
[:SENSe]:BANDwidth Subsection
63, which is a flowchart that illustrates VBW and
Remote Command Reference
311