H i-FIR correlations for IVC 1 and IVC 2 at 857 GHz (left) and 3000 GHz (right). The H i is integrated between −100 km s^-1 ≤ v_LSR ≤ + 100 km s^-1. The black solid line is the linear fit applying Eq. (1)for IVC 1 and the dashed black line for IVC 2. For IVC 2 the fit is restricted to N_H i ≤ 2.0 × 10²⁰ cm^-2, above which a FIR excess due to H₂ is evident. For IVC 2 the spread in N_H i for given I_ν is due to a second FIR maximum that is not associated with an H i peak (Fig. 12).