Details for different cufftXtSubFormat_t types

Hi, I saw multiple types for cufftXtSubFormat_t. cuFFT :: CUDA Toolkit Documentation
Where can I find a more detailed explanations (with pictures) for differences across these types? All the multi-GPU FFT examples I have seen so far use CUFFT_XT_FORMAT_INPLACE. In which case should I use other types? Thanks?