(07 Jun 2024, 9:01 pm)Jimmi wrote Not necessarily, another number can be added on, especially if it closely mirrors another route, i.e. X71 - X72 has been taken off the X71 registration and registered separately.
There's also an X32 on the X30/X31 registration.
Not forgetting the new X73 - which, judging by the details on the VOSA page, is the old 6 route reinstated.