It depends on where you place the letter RUB, HUB, CUB, BOB, DUB were sets not cars. The A in the sleaping cars is in a diferent possi to the A in the PHA. The A in the AB, ABX and AK means "special" carriage. The A and M in all sleaping cars again has a different meaning, It was explained to me but I can't remember but basicly means beds and stuff. rgds