Distributions of the first three moments of the DIB profiles for the entire catalog (black lines) and selected ranges of longitudes (red, green, and blue lines): Left: equivalent width W_DIB. The raw observed distribution is shown in black, and overplotted in gray is the completeness-corrected distribution (Appendix B). The gray shading marks the range of W_DIB where for most observed feature amplitudes, the catalog is less than 20% complete. Middle: offset of the measured line center λ from the calculated rest wavelength (Section 4.2). The shape of this distribution is driven by the relative velocities of the DIB features, as explored in Section 4.3. The colors of the lines are the same as in the left panel. Right: profile width σ. The colors of the lines are the same as in the left panel. The right-hand y axis indicates the catalog completeness in σ as a function of feature amplitude, C(σ; |A|), as traced by the gray lines for two representative amplitudes: dotted for the median A (0.06) and dashed for the 90th percentile value (0.09).