There are other "oddball" combinations, such as 8E1 and 8O1, which sends
a 9-bit data frame. You can see datasheets on some UARTs as well as MCU
UARTs that support the 9 bit packet.
Also, don't/doesn't TDD (5 level code) use 5E2 or some such. Same for
Telex/TWX.
--Chuck