  A binary extended 1-perfect code $\mathcal C$ folds over its kernel via the
Steiner quadruple systems associated with its codewords. The resulting folding,
proposed as a graph invariant for $\mathcal C$, distinguishes among the 361
nonlinear codes $\mathcal C$ of kernel dimension $\kappa$ with $9\geq\kappa\geq
5$ obtained via Solov'eva-Phelps doubling construction. Each of the 361
resulting graphs has most of its nonloop edges expressible in terms of the
lexicographically disjoint quarters of the products of the components of two of
the ten 1-perfect partitions of length 8 classified by Phelps, and loops mostly
expressible in terms of the lines of the Fano plane.
