24983 is a "Multi-Select" or "Status Bit" function of the FR Dispatch A1 talkgroup (24976).
Here is a breakdown of Motorola status bits:
ID+0 Normal Talkgroup
ID+1 All Talkgroup
ID+2 Emergency
ID+3 Talkgroup patch to another
ID+4 Emergency Patch
ID+5 Emergency multi-group
ID+6 ?
ID+7 Multi-select (initiated by dispatcher)
ID+8 DES/DVP Encryption talkgroup
ID+9 DES All Talkgroup
ID+10 DES Emergency
ID+11 DES Talkgroup patch
ID+12 DES Emergency Patch
ID+13 DES Emergency multi-group
ID+14 ?
ID+15 Multi-select DES TG
Taken from the invaluable Mark's Scanners pages here:
Easier to Read BCD396T/UBCD396T Manual
For the Motorola systems I monitor, I always program in the +0 TG, plus the other "variations" up to +7, just so I don't miss anything, ever. I don't bother w/the the +8 and above DES stuff, since you can't hear it with a scanner anyways.