  We aim to provide new empirical clues about macroturbulent spectral line
broadening in O- and B-type stars to evaluate its physical origin.
  We use high-resolution spectra of ~430 stars with spectral types in the range
O4-B9 (all luminosity classes). We characterize the line-broadening of adequate
diagnostic metal lines using a combined FT and GOF technique. We perform a
quantitative spectroscopic analysis of the whole sample using automatic tools
coupled with a huge grid of FASTWIND models. We also incorporate quantitative
information about line asymmetries to our observational description of the
characteristics of the line-profiles, and present a comparison of the shape and
type of line-profile variability found in a small sample of O stars and B
supergiants with still undefined pulsational properties and B main sequence
stars with variable line-profiles.
  We present a homogeneous and statistically significant overview of the
(single snapshot) line-broadening properties of stars in the whole O and B star
domain. We find empirical evidence of the existence of various types of
non-rotational broadening agents acting in the realm of massive stars. Even
though all of them could be quoted and quantified as a macroturbulent
broadening from a practical point of view, their physical origin can be
different. Contrarily to the early- to late-B dwarfs/giants, which present a
mixture of cases in terms of line-profile shape and variability, the whole
O-type and B supergiant domain (or, roughly speaking, stars with M_ZAMS > 15
M_sol) is fully dominated by stars with a remarkable non-rotational broadening
component and very similar profiles (including type of variability). We provide
some examples illustrating how this observational dataset can be used to
evaluate scenarios aimed at explaining the existence of sources of
non-rotational broadening in massive stars.
