  Smooth algebraic plane quartics over algebraically closed fields have 28
bitangent lines. Their tropical counterparts often have infinitely many
bitangents. They are grouped into seven equivalence classes, one for each
linear system associated to an effective tropical theta characteristic on the
tropical quartic. We show such classes determine tropically convex sets and
provide a complete combinatorial classification of such objects into 41 types
(up to symmetry).
  The occurrence of a given class is determined by both the combinatorial type
and the metric structure of the input tropical plane quartic. We use this
result to provide explicit sign-rules to obtain real lifts for each tropical
bitangent class, and confirm that each one has either zero or exactly four real
lifts, as previously conjectured by Len and the second author. Furthermore,
such real lifts are always totally-real.
