  We explore theories of dark matter in which dark matter annihilations produce
mono-energetic gamma rays ("lines") in the context of effective field theory,
which captures the physics for cases in which the particles mediating the
interaction are somewhat heavier than the dark matter particle itself. Building
on earlier work, we explore the generic signature resulting from SU(2)xU(1)
gauge invariance that two (or more) lines are generically expected, and
determine the expected relative intensities, including the possibility of
interference between operators.
