  The Bol operators are unary differential operators between spaces of weighted
densities on the 1-dimensional manifold invariant under projective
transformations of the manifold. On the $1|n$-dimensional supermanifold
(superstring) $\mathcal{M}$, we classify analogs of Bol operators invariant
under the simple maximal subalgebra $\mathfrak{h}$ of the same rank as its
simple ambient superalgebra $\mathfrak{g}$ of vector fields on $\mathcal{M}$
and containing all elements of negative degree of $\mathfrak{g}$ in a
$\mathbb{Z}$-grading. We also consider the Lie superalgebras of vector fields
$\mathfrak{g}$ preserving a contact structure on the superstring $\mathcal{M}$.
We have discovered many new operators.
