  The BFV-formalism was introduced to handle classical systems, equipped with
symmetries. It associates a differential graded Poisson algebra to any
coisotropic submanifold $S$ of a Poisson manifold $(M,\Pi)$. However the
assignment (coisotropic submanifold) $\leadsto$ (differential graded Poisson
algebra) is not canonical, since in the construction several choices have to be
made. One has to fix: 1. an embedding of the normal bundle $NS$ of $S$ into
$M$, 2. a connection $\nabla$ on $NS$ and 3. a special element $\Omega$. We
show that different choices of the connection and $\Omega$ -- but with the
tubular neighbourhood fixed -- lead to isomorphic differential graded Poisson
algebras. If the tubular neighbourhood is changed too, invariance can be
restored at the level of germs.
