  We study the objects (called spectral branes or S-branes) which are obtained
by imposing non-local spectral boundary conditions at the boundary of the world
sheet of the bosonic string. They possess many nice properties which make them
an ideal test ground for the string theory methods. Depending on a particular
choice of the boundary operator S-branes may be commutative or non-commutative.
We demonstrate that projection of the B-field on the brane directions (i.e. on
the components which actually influence the boundary conditions) is done with
the help of the chirality operator. We show that the T-duality transformation
maps an S-brane to another S-brane. At the expense of introducing non-local
interactions in the bulk we construct also a duality transformation between
S-branes and D-branes or open strings.
