Teledyne LeCroy LabMaster 9Zi-A - Manual (Page 160)

LabMaster 9 Zi-A
152 922157-00 Rev A
Pushing the Intensity knob changes the Persistence status in the following
ways.

OFF - When the button hasn't been pushed, it may be turned to
control the trace Intensity control value.

Analog Persistence - When the button is pushed once, the
waveform resembles a trace on a phosphor oscilloscope. Turning the
knob affects persistence with a blended form of Intensity and
Saturation. As the knob is turned clockwise, the Intensity value
increases while the Saturation value decreases. The opposite occurs
when the button is turned counter clockwise.

Color Persistence - The button behaves the same way as Analog.
However, the grid display shows a color waveform where red
indicates most frequent occurrences while blue denotes the less
frequent.
Instead of using the knob, you can provide values for Intensity (same
control on Display and Persistence dialogs) or Saturation controls.