>(ii) Maps, charts, codes and other documents and navigational equipment necessary, in addition to any other equipment required under this Order, for the intended flight of the aircraft including any diversion which may reasonably be expected.<
This is what the ANO says.
I was always under the impression that there is a requirement to carry topo charts of the route even when flying IFR.
Maybe this has changed but when I was flying for the airlines we always had topo charts in the library.
I guess you might need them if you lose all radios etc and have to continue visually - heaven forbid!