>    \N{name}   : named character
>    \UXXXXXXXX : 32-bit hexadecimal ordinal (e.g. \U0010ffff)
>    \uXXXX     : 16-bit hexadecimal ordinal (e.g. \uffff)
>    \xXX       : 8-bit hexadecimal ordinal (e.g. \xff)
>    \OOO       : 9-bit octal ordinal (e.g. \777)
>    \OO        : 6-bit octal ordinal (e.g. \77)
>    \O         : 3-bit octal ordinal (e.g. \7)

Note that bytes literals do not implement \N, \U, and \u escape sequences -- e.g. b'\N{SPACE}' is literally just those 9 bytes, not b' '. Also, in bytes literals 9-bit octal sequences wrap around for the [256, 511] range -- e.g. b'\400' ==  b'\000' == b'\x00' and b'\777' == b'\377' == b'\xff'. I don't know whether the latter is intentional. I'd prefer for the compiler to raise a syntax error in this case. Asking for a byte value in the range [256, 511] is nonsense.