Order of buffer3D elements in an array

Dear.
Let an output buffer be 3D = a[I,J,K]. It is too convenient to use on GPU side
my_buffer[l_ind] = 0.5f;
Is there any analog on a host side in CPP-file, e.g.,
uint3 ind = make_uint3(2, 4, 7);
memcpy((void *)outSpectra, my_buffer->map(), width * height * SPECTRUM_SIZE * sizeof(float));
float ff = outSpectra[ind]; // or the like
If no then specify please the order of elements in a buffer3D.
IMO this information should be in “NVIDIA® OptiX™ Ray Tracing Engine Programming Guide”.

Have a look at this topic, this was already asked before:

https://devtalk.nvidia.com/default/topic/601137/reading-3d-buffers-on-cpu/?offset=2#3932163

Thanks,

sorry I’ve forgot that post.
Nevertheless I would prefer symmetry if possible.