CQM016E You are currently viewing the last available interval in this navigational direction. Please navigate in the opposite direction to view other available intervals by pressing either the PF4 or PF6 key.

Explanation
 The PREV command was requested while viewing the
last interval. Because the interval being viewed is the first (oldest)
interval, no previous intervals can be viewed. 

User response
   No action is required.
 If you would like to view intervals other than the interval you are currently viewing, you can
    issue the INTV command to view the available intervals and select those you want to view from a
    list.