Residual maps (data minus best-fit model, in sigma units) in dust optical depth (σ_τ353) and in γ-ray counts in the 0.4–100 GeV band (σ_γ) obtained when including different sets of gaseous components in the models: without (left) and with (middle) the DNM and COsat components in addition to the H i, CO, and free-free templates; a close-up view (right) of the γ-ray residuals without (top) and with (bottom) the free-free map. The grey circles in the left-hand column highlight a DNM shell. The thin black contours outline the shape of the CO clouds at the 7 K km s^-1 level chosen to separate DNM and CO_sat components. The thick black contours in the right-hand column outline the shape of the NGC 1499 and G159.6-18.5 H iiregions at the 2 × 10⁴ Jy sr^-1 level in free-free emission at 70 GHz. The models are derived for an H ispin temperature of 400 K.