The W(5797)/W(5780) ratio plotted against E_(B−V). The distribution peaks at an E_(B−V) of  ~0.25 mag, indicating most optimal conditions for formation of the 5797 Å DIB carrier and the destruction c.q. insufficient excitation of the molecule giving rise to the 5780 Å DIB. Nonetheless, the significant scatter suggests that processes additional to dust extinction are important.