Scheme of the data reduction process for the NIRSpec data of PJ308-21. The data reduction is divided into three stages, each of them consisting of several steps. Stage 1 is independent from the JWST instrument and mode, unlike stage 2 and 3, for which we present the steps for NIRSpec/IFU. We skip some pipeline steps (boxes with gray tilted lines) and introduce additional steps (orange boxes) to improve the data reduction (see Sect. 2).