Tensionless Branes and Discrete Gauge Symmetry
  We show that the tensionless branes found recently on non-BPS D-branes using non-commutative field theory are in fact gauge equivalent to the vacuum under a discrete gauge symmetry. We also give a simple construction of the D(2p)-branes in IIA theory starting from a single non-BPS D9-brane. 
Jeffrey A. Harvey, Per Kraus, and Finn Larsen