Now that you understand how these work, I also want to clear something up. Some manufacturers call there "Privacy tones" or Privacy codes" or even act like they are different channels, and advertise that the radio has "968 channel combinations." All of this is completely untrue. CTCSS and DCS don't stop anyone from listening to you, they just stop you from hearing other people. If someone has a radio with no CTCSS and DCS on, they will be able to hear everyone on the channel, including people using CTCSS and DCS.
Also, CTCSS and DCS do not make additional channels. If someone is on the same channel with a different code, then its not a different channel. If you stand next to them and both transmit, your radios will interfere because they will be trying to use the same channel at the same time. On PMR446, there are only 8 channels, and no CTCSS or DCS can change that.