Top: Stage 1 of the NIRSpec processing pipeline: generation the count-rate maps starting from the exposure up-the-ramp integration cube. Bottom: Stage 2 of the NIRSpec processing pipeline for a MOS observation for point-like sources. The processing is applied to each source in the target catalogue that provide the pipeline with a source sky position, MOS aperture coordinates (k, i, j) and relative coordinates within the slitlet. Steps 2, 5 and 6 are valid for an ideally-centred source, steps 3 and 7 introduce the necessary corrections taking into account the actual source position relative to the slitlet centre. Yellow ovals indicate the reference calibration data necessary to perform the operation.