Energy spectra measured with SPI during the INTEGRAL mission. Above: mission-integrated all-detector spectrum (orbits 43-1730). This allows us to identify even the weakest background features. Inserts show spectral regions near the two brightest celestial lines, the 511 keV line from positron annihilation (lower-left), and the ²⁶Al line at 1809 keV from diffuse nucleosynthesis throughout the Galaxy (upper-right). Middle and below: same spectrum, now accumulated just for detector No. 0 and orbit No. 1000 (middle) , and for one detector (No. 0) and one pointing (below).