  During the past decade or so, measurements of Galactic HI absorption using
VLBI against extra-galactic sources, as well as multi-epoch observatios in
pulsar directions, have detected small-scale transverse variations
corresponding to tens of AU at the distance of the absorbing matter. Hitherto
these measurements have been interpreted as small-scale structure in the HI
distribution with densities n_{HI} ~ 10^4-10^5 per cc, orders of magnitude
greater than those of the parsec-scale structure. Naturally it is difficult to
imagine how such structures could exist in equilibrium with other components of
the ISM.
  In this paper we show that structure on all scales contributes to the
differences on neighbouring lines of sight, and that the observed differences
can be accounted for by a natural extension of the distribution of
irregularities in the distribution of HI opacities at larger scales, using a
single power law. This, in our opinion, should put an end to the decades long
puzzle of the so-called small-scale structure in HI and other species in the
Galaxy.
