They are new interop chans that Charles County uses. They are tagged with the geographical area in which the units are active. Recently a recovery operation was conducted for a missing boater whose last know location was near Marshall Hall boat dock across the river from Gunston Cove Va. DNR, the Coast Guard and VA units participated. Dispatchers use the geographical name and channel number to "confuse" the scanning public and media. The same talk groups would have another geographical tag should another incident take place.Can you describe a little more what you mean by "Marshall Hall?" Are these analog channels used for that part of the county, or something like that?