Clarion NX501 Owner's Manual & Installation Manual page 152

This is not a button. This line shows the current size of the trip database, the sum
of all trip and track logs saved.
Track logs, the sequence of the positions given by the GPS receiver, can be
saved together with trip logs. They can later be displayed on the map. You can let
the application save the track log whenever it saves a trip.
83 NX501/NZ501 English