  We show that the existence of a tachyon vacuum puts tight restrictions on the
form of solutions to the equations of motion of string field theory. In
particular, we demonstrate that every solution can be written as a - formal -
gauge transformation of the tachyon vacuum. In order for a solution to be
non-trivial, this gauge transformation must be singular and we argue that this
will happen when the gauge transformation annihilates a projector of the
star-algebra. We comment on possible applications of the formalism to finding
new solutions.
