You may want to look at my slice timing page. As described in the [url=https://www.siemens-healthineers.com/siemens_hwem-hwem_ssxa_websites-context-root/wcm/idc/groups/public/@global/@imaging/@mri/documents/download/mdaz/nzmy/~edisp/mri_60_graessner-01646277.pdf]Siemens white paper, [/url]axial EPI slices are always saved in the foot-head order, regardless of the order that the data was acquired. Therefore, the first slice in the array corresponds with the slice closest to the foot, and the final slice saved to disk is the most superior. The slice timing array in the JSON file suggests data is saved in an interleaved descending order, with the most superior slice acquired first (time zero). So the order slices were acquired was 32,30,28..2, 31,29,...1, with the final (most inferior) slice acquired 1.9425s after the first (most superior) slice. See the BIDS specification for the formal definition. Note that storing the timing is more useful than storing the order: sparse scans can have a delay after the final slice before the next slice in the subsequent volume. Likewise, for multi band sequence you will have multiple slices with the same slice times.