Turn off VVX 501/601 backlight?

On the VVX 501 and 601, can the backlight be turned off when the phone is idle?

This User Guide (5.3.0) says yes:

http://plcmtechnet.com/documents/voice-conferencing/desktop-phones/vvx-business-media-phones/vvx-300/5-3-0/user-guide/customize-your-phone#toc-SettheBacklightIntensityandTimeout

"You can change the Backlight On intensity and the Backlight Idle intensity separately, and you can choose a high, medium, or low intensity, or turn off the backlight entirely."

The Admin Guide (5.5.0, page 385) says no:

up.backlight.idleIntensity

VVX 300/301/310/311 = 0, 1, 2, 3

All other phones = 1, 2, 3
The brightness of the LCD backlight when the phone is idle. 1 – low, 2 – medium, and 3 – high.