I made an inquiry on this subject on the "Sticky" thread, but not having any results for 5 days or so, thought I'd start a new thread - I've "recently" (15 months or so) returned to the Seattle/Tacoma are after spending 15 years in the St. Louis area. I'm attempting to better understand the utilization of certain talk groups in the Seattle/King County Public Safety system; specifically the PSOPS and ERT talk groups. Are these talk groups available for use by any of the various municipalities participating in the system? Are certain groups assigned to certain agencies? If so, which ones use which group? What is the difference in use between PSOPS and ERT- and what does ERT stand for? How does the use of these talk groups differ from the TAC talkgroups? I'm trying to organize the various system talk groups into scan lists on my GRE PSR-500 in such a way as to avoid scanning ALL the ERT/PSOP/TAC groups in every scan list. Another question is in regard to the use of the Valley NARC talkgroups. Is this King County PD only or do various municipalities use it as well? Thanks in advance for your insight and assistance.