Gamma-ray spectra extracted from four sky regions: full-sky (top-left), intermediate latitudes (10° < |b| < 40°, top-right), inner Galaxy (|b| < 8° ∧80° < l < 280°, bottom-left), and outer Galaxy (|b| < 8° ∧l < 80° ∧l > 280°, bottom-right). The total gamma-ray spectrum (blue solid line) is computed as the sum of three basic emission components: inverse Compton (red solid line), bremsstrahlung (orange solid line), and π⁰-decay (green solid line). For the pion decay we show the contributions of HI (green dashed line) and of H₂ (green dotted line) separately.