It is heartening, therefore, to see that much maligned First Great Western is doing its level best to communicate with passengers in a language they understand.
Pictured below is a note seen taped to the nappy changing facilities on FGW unit 158955 last weekend.
Clearly attempting to avoid the use of OOU an unknown FGW wag has helpfully clarified the problem by hand.
Nice to see the use of the bracketed expression, which not only explains the precise condition of the nappy changing facility but also of the mother who wished to use it.
Campaign for Plain English 'Crystal Marks' all round!