Serial / network I/O is disregarded, because it works independent of memory and disc space. However a letter can be added to define communication device classes.
'''Defined classes are:'''
*Class 0 CPC: 64 KB RAM, Cassette-Drive (CPC-464)
*Class 1 CPC: 64 KB RAM, 3" drive (CPC-664)
*Class 2 CPC: 128 KB RAM, 3" drive (CPC6128)
*Class 3 CPC: 64 KB RAM, Cassette-Drive, Cartridge-Slot, Plus-Features
*Class 4 CPC: 128 KB RAM, Floppy-Drive, Cartridge-Slot, Plus-Features, Light-Gun-Compatible-Joy-Port-Cable-Connector!!!1elf!
*Class 5 CPC: More than 128K RAM, HxC, Symbiface II, ROM-Box, FOSfree,
'''Defined communication classes are:'''