theory are collected. They are related to determining the chromatic number of the q-
analogues of Kneser graphs. For the proof one needs results on the number of 0-secant
subspaces of point sets, so in the second part of the paper recent results on the structure of
point sets having few 0-secant subspaces are discussed. Our attention is focussed on the
planar case, where various stability results are given.