  J. Boyle classified 1-handles attached to surface-knots, that are closed and
connected surfaces embedded in the Euclidean 4-space, in the case that the
surfaces are oriented and 1-handles are orientable with respect to the
orientations of the surfaces. In that case, the equivalence classes of
1-handles correspond to the equivalence classes of cords attached to the
surface-knot, and correspond to the double cosets of the peripheral subgroup of
the knot group. In this paper, we classify cords and cords with local
orientations attached to (possibly non-orientable) surface-knots. And we
classify 1-handles attached to surface-knots in the case that the surface-knots
are oriented and 1-handles are non-orientable, and in the case that the
surface-knots are non-orientable.

Geometric Topology