Pro Tools | First lets you set any track timebase to either sample-based or tick-based. You can also set the Timeline to be viewed as tick-based or sample-based.

New tracks in Pro Tools | First are tick-based by default. This means that if an audio or MIDI clip is located at a particular Bar|Beat location, it will not move from that Bar|Beat location if the tempo changes in the project—though its sample location will change.

You can select whether a track is sample-based or tick-based when it is created, or change timebases later.