Keithley 2461 Quick Start Manual page 22

HELP
You can display help screens for the menu items and buttons. The
help screens give a brief description of the option that the menu or
button sets, and remote commands related to the setting. To display
the description, highlight the menu item or button and press the
HELP key. The graphic below shows an example of the help when
you are on the System Events tab of the event log.
FUNCTION
The FUNCTION key opens the FUNCTION selection dialog
box, which allows you to select the source, measure, and digitize
functions.
The instrument saves many of the commands with the source or
measure function that was active when you set them. For example, if
you set the measure function to current and you set a value for
NPLCs, the instrument saves the NPLC value for that measure
function. When you change the measure function to voltage, the
NPLC value changes to the value that was last set for the voltage
measure function.