Got it ! LAV = "Load Average"
The system has a calculated attribute called a load average (LAV).
The operations of some processes can be controlled based on the LAV.
The LAV is a floating point value.
eg. set sendmail to stop executing when the LAV exceeds a specified value. ie the system (CPUs, etc) are highly utilized.
In the case you are stating it seems logical that the options that
you confugure under that menu for power are acted on only if the
system load average (LAV) is higher than a threshold value.
In Debian design sendmail checks the system load average,
and stops processing mail when the LAV exceed a specified threshold,
so as to allow other (more important) processes to run.
There are KDE applications (eg. klavg) that show the system's current
I've had a dig around but I cannot find any documentation about how
Debian Linux calculates (or sets) the LAV