I am monitoring Charles County traffic on the Faifax County Marshal Hall 1 TG. I know the purpose of this talkgroup is normally to be used for potomac river communications between Fairfax County, Charles County, and PG County for river incidents. Charles County is on this talkgroup making reference to TG 10A10 for PG County A824 responding mutual aid. Any ideas what that 10A10 talkgroup would be? Any idea what traffic is normally transmitted on this talkgroup on the Fairfax P25 system?