Join Date: Jan 2012
Location: Not every shadow, but any shadow
If you are talking about "required" as meaning what's in the rules the only requirement I can find is in the deployment section, Pg 121. I've not found anything after that that says you must tell them.
Colour Coding works fine for me, as I said I make sure they all match up and in a five turn game I've not ever found the time to play "Musical Rhinos" with my troops.
Most guys around my way play a fairly natural game and few of us sit there calculating the odds to the nth degree before shooting/moving/assaulting whatever.
It's rare that anyone would ask me what was in a vehicle when making a targeting choice, most of the time who tells who what and were and why and when is not all that much of a concern.