The longitude–velocity (l–vLSR) diagram of the DIB sample. Gray points are the measurements along individual sightlines, and the red circles indicate the median and median deviation in each Δl = 10° bin. Overplotted are velocity curves from a simple disk rotation model (see the text) for Galactocentric circles with RGC = 6 kpc (solid), 7 kpc (dotted), 9 kpc (dashed), and 11 kpc (dot–dashed).