Most plates have 7 characters, but private and older plates can be shorter, like K1 ABZ.
Any length finds every plate that starts or ends with what you typed, however long it is. Leave
empty boxes _ at the end if you
saw the start, or at the start if you saw the end.
It can take a little longer and usually finds more vehicles, so add a make or colour if there are too many.
Any length only works if the first or the last box is left empty.