  We discuss orientational ordering in monolayers of solid hydrogen in view of
recent experimental findings in NMR studies of
(\QTR{it}{ortho)}$_{c}$-(\QTR{it}{para)}$_{1-c}$-hydrogen mixtures on boron
nitride substrate. Analysis of the temperature-concentration behavior for the
observed NMR frequency splitting is given on the basis of a two-dimension
($J=1)_{c}$-($J=0)_{1-c}$-rotor model with the quadrupolar coupling constant
$\Gamma_{0}=0.50\pm 0.03$ $K$ and the crystalline field amplitude
$V_{0}=0.70\pm 0.10$ $K$ derived from experiment. The two distinct
para-rotational (PR) short-range ordered structures are described in terms of
the local alignment and orientation of the polar principal axis, and are shown
to be due to the interplay between the positive and negative crystalline
fields. It is shown that the observed below the 2D site percolation threshold
$c_{p}=0.72$ local structures are rather different from the ferromagnetic-type
PR ordering suggested earlier by Harris and Berlinsky.
