  The Multi-slit Solar Explorer (MUSE) is a proposed mission aimed at
understanding the physical mechanisms driving the heating of the solar corona
and the eruptions that are at the foundation of space weather. MUSE contains
two instruments, a multi-slit EUV spectrograph and a context imager. It will
simultaneously obtain EUV spectra (along 37 slits) and context images with the
highest resolution in space (0.33-0.4 arcsec) and time (1-4 s) ever achieved
for the transition region and corona. The MUSE science investigation will
exploit major advances in numerical modeling, and observe at the spatial and
temporal scales on which competing models make testable and distinguishable
predictions, thereby leading to a breakthrough in our understanding of coronal
heating and the drivers of space weather. By obtaining spectra in 4 bright EUV
lines (Fe IX 171A, Fe XV 284A, Fe XIX-XXI 108A) covering a wide range of
transition region and coronal temperatures along 37 slits simultaneously, MUSE
will be able to "freeze" the evolution of the dynamic coronal plasma. We
describe MUSE's multi-slit approach and show that the optimization of the
design minimizes the impact of spectral lines from neighboring slits, generally
allowing line parameters to be accurately determined. We also describe a
Spectral Disambiguation Code to resolve multi-slit ambiguity in locations where
secondary lines are bright. We use simulations of the corona and eruptions to
perform validation tests and show that the multi-slit disambiguation approach
allows accurate determination of MUSE observables in locations where
significant multi-slit contamination occurs.
