  When gauging a $(d-1)$-form symmetry in $d$ spacetime dimensions, one
formally expects the gauged theory to carry a dual $-1$-form symmetry. This
work focuses on the study of such symmetries, in particular via the
spacetime-filling topological operators that implement them, in two-dimensional
field theory (with an eye towards general quantum field theory). As theories
with $(d-1)$-form symmetries are known to be equivalent to direct sums of local
theories, we review how gauging a $(d-1)$-form symmetry projects onto a single
component in this sum, and explain how gauging the resulting $-1$-form symmetry
restores the direct sum.
