Distributions of rotational velocities for normal stars in different mass subsamples: shaded histograms are the observed vsini; solid thick lines are the distributions of equatorial velocities and the gray strips are their associated variability bands. The dashed lines stand for the Maxwellian fit, whose parameters are given in Table 4. The mass range for each subsample is indicated in the corresponding panel, together with the number of stars. The histograms are normalized to fit the probability density scale.