In this paper, we give an exposition of Gabber's proof of the Bloch-Ogus
theorem for étale cohomology with locally constructible torsion
coefficients. We then abstract the ingredients of the proof to
give an axiomatic treatment of it. The axioms involved are much less
demanding than those of Bloch and Ogus and therefore apply to a vaster
array of cohomology theories. We also give a detailed treatment of
universal exactness à la Grayson, as well as several applications.
This paper has appeared in Fields Institute for Research in Mathematical
Sciences Communications Series 16, A.M.S., 1997, 31-94, so the dvi files have
been removed. See http://www.fields.utoronto.ca/pubs.html.