They are not tested at all in either VFR or IFR Comms. They might turn up in Radio Navigation or, as CAT 3 says, in AGK but I haven't had any reports of them in the exams recently. The Radio Nav exam is based heavily on the old CAA Radio Aids question database and they used to ask some questions on them in 't old days so most schools include them 'just in case'. Suggest you remember A3E and J3E, A8W and A9W, P0N and the NDB ones, N0N, A1A and A2A.