“Marcus Trunked” refers to Marcus Communications, a commercial business that will rent or lease two-way radio communications (among other things). Marcus assigns clientele a unique TalkGroup to each and they share a trunked system licensed to Marcus. This may be an over simplification of what’s happening but it explains why different services are being heard on the same frequency (that is scanning using the “Search” option for TG’s), it’s a trunked system populated by ambulance company’s, tow trucks, basically anyone looking for two-way radio between vehicles and headquarters.