The +/-z there refer to with respect to the direction z is changing, not whether it goes from I to S or S to I. If the first slice acquired was the most superior and the last the most (or second most, depending on the parity) inferior, AND if the orientation shows S to I (e.g. RAS) in 3dinfo, say, then the timing pattern should be alt+z.
Note that this is a relative comparison between the temporal order of slices and the order of slices on disk. If they are the same it will be '+', if not, a '-'.
What does 3dinfo -orient say about this dataset?
- rick
