Reading voxel data

Hi,

it's me again. I need information on how a dataset (composed of
voxels) is organized and what the code to read it looks like. Let's
say a got a 256x256x128 dataset and UCHARS. I think the voxels are
like (z,y,x, property).

By now that is all the info i got. I appreciate any help, suggestion,
bibliographic entry, etc. Thanks in advance,

Victor
.