And some of you already know, I listen to CHP a lot. As a retired cop I really don't want to listen to routine law enforcement calls, even though I can't because they're encrypted.
I'm figuring out the areas that individual black and white shoes. But what are David units? What are units such as Inland 5? I think I figured out that Robert units are Reserve units. Or are they commercial inspection units?
"D" Unit Call Signs are assigned to Officers in Special Duty assignments such as Accident Investigation Officers, Court Officers, Public Affairs Officer, VIN Officer, etc. that are not assigned to Road Patrol or a Beat. The "D" call signs are used in the field area office commands such as San Bernardino, Riverside, etc..
Inland call signs are assigned to Personnel assigned to the Division and the Division has management responsility of the field commands known as Area Offices. I. E. "Inland 1 would be the Division Commander (Deputy Chief), "Inland 2 & 3" would be used by the Assistant Division Commanders (Assistant Chiefs). "Inland 5" may be a Lieutenant in the Inland Division Command.
There are no reserve Officers in the Highway Patrol. They may be either Units assigned to Patrol units not assigned to a specific beat assignment or a dedicated Radar Unit.
Most Commercial Enforcement Units are assigned to the Division Command now. They would normally be assigned a Division number i.e. in Inland Division they would have an "Inland" number.
Some years ago, they were assigned to Commercial Inspection Facilities or Area Commands and each Inspection Facility where there own Command. If a Commercial Enforcement Officer, formally known as "Mobile Road Enforcement (MRE) units, were assigned Unit numbers that began with "850". I.E. a Commercial Officer assigned to Santa Ana Area would have a radio call sign of "86-850".