2.2.3-10 Labeling Multifunction Keys

If a key is used for more than one function, the function currently available should always be indicated to the user.

Additional Information:
If a key is used for just two functions, depending upon defined operational mode, then alternate illuminated labels might be provided on the key to indicate which function is current. In those circumstances, it is preferable that only the currently available function is visible, so that the labels on a group of keys will show what can be done at any point. If key function is specific to a particular transaction, an appropriate guidance message on the user's display should be provided to indicate the current function.