  When we examine the chirality or observed handedness of the chromospheric and
coronal structures involved in the long-term build-up to eruptive events, we
find that they evolve in very specific ways to form two and only two sets of
large-scale chiral systems. Each system contains spatially separated components
with both signs of chirality, the upper portion having negative (positive)
chirality and the lower part possessing positive (negative) chirality. The
components within a system are a filament channel (represented partially by
sets of chromospheric fibrils), a filament (if present), a filament cavity,
sometimes a sigmoid, and always an overlying arcade of coronal loops. When we
view these components as parts of large-scale chiral systems, we more clearly
see that it is not the individual components of chiral systems that erupt but
rather it is the approximate upper parts of an entire evolving chiral system
that erupts. We illustrate the typical pattern of build-up to eruptive solar
events first without and then including the chirality in each stage of the
build-up. We argue that a complete chiral system has one sign of handedness
above the filament spine and the opposite handedness in the barbs and filament
channel below the filament spine. If the spine has handedness, the observations
favor its having the handedness of the filament cavity and coronal loops above.
As the separate components of a chiral system form, we show that the system
appears to maintain a balance of right-handed and left-handed features, thus
preserving an initial near-zero net helicity. Each individual chiral system may
produce many successive eruptive events above a single filament channel.
