I just started an ATmega32 project using AVR Studio 4.09 and got an error while assembling it. It pointed to my initialization of the SFIOR register and did not know what ADTS0 was. I opened m32def.inc in the AVR assembler's path and noticed that ADTS2,ADTS1,ADTS0 and the undefined bit 4 were named RPDD, RPDC, RPDB, RPDA.
I upgraded to AVR Studio 4.10 but it is still the same m32def.inc file. Oh well, going to changed the include file.