Garmin GTR 225 Pilot's Manual page 37

When the Count Down Timer reaches 0:00, it will continue counting as a
Count Up value. The Count Down Timer that is counting up will be highlighted.
A Count Up Timer will continue counting separately.
Figure 3-36 Count Down Timer Value Now Counting Up
190-01182-00 Rev. A
Garmin GTR 225/225A/225B Pilot's Guide
Count Down Timer Value
Highlighted When Counting Up
3-19