From the Manual Pg 38 (for future reference)
Each talkgroup on a trunked radio system is identifi ed by a
talkgroup ID. You can store talkgroup IDs automatically while
scanning the trunked system in Open mode, or manually by
entering the IDs directly.
To automatically store a talkgroup ID, press TRUNK when
the scanner stops on a voice channel transmission or
when a talkgroup ID is indicated in the manual mode. The
ID of the active talkgroup is automatically stored in the
next available ID memory location. Your scanner’s display
indicates where the ID was stored as ID save X-YY, and then
changes to ID#ZZZZZ, where X is the sub-bank number, YY is
the ID number within the sub-bank, and ZZZZZ is the stored
talkgroup ID code. If the ID has already been stored when
you press TRUNK, ID was saved appears on the scanner’s display