  We classify the half-supersymmetric "domain walls", i.e. branes of
codimension one, in toroidally compactified IIA/IIB string theory and show to
which gauged supergravity theory each of these domain walls belong. We use as
input the requirement of supersymmetric Wess-Zumino terms, the properties of
the E11 Kac-Moody algebra and the embedding tensor formalism. We show that the
number of half-supersymmetric domain walls is a multiple of the number of
corresponding central charges in the supersymmetry algebra, where the
multiplicity is related to the degeneracy of the BPS conditions.
