Let M and N be Q-manifolds
and let i be a locally flat embedding of N into M. It is shown that if N = Q × Rn,
then i must be flat. The following version of the Kirby-Siebenmann codimension 2
tubular neighborhood theorem is proved. If i is locally flat of codimension 2, then the
embedded submanifold has a tubular neighborhood, and any two such tubular
neighborhoods are isotopic. Among the tools developed is a relative version of Z-set
unknotting.