Schematic view of the NISP instrument detailing its subsystems. Right: view of the whole instrument as integrated. Left: detailed view with an open wheel cavity, showing the locations of the two wheels to select spectral elements. Not shown are the ‘warm’ electronics, which are used for commands and data processing; they are located away from the main NISP instrument assembly in Euclid’s service module (Maciaszek et al. 2016). The subsystem names and functions are described in the main text.