  In her paper "Generalized matroids and supermodular colourings", Tardos
studied special delta-matroids obtained from sequences of Higgs lifts; these
are the full Higgs lift delta-matroids that we treat and around which all of
our results revolve. We give an excluded-minor characterization of the class of
full Higgs lift delta-matroids within the class of all delta-matroids, and we
give similar characterizations of two other minor-closed classes of
delta-matroids that we define using Higgs lifts. We introduce a minor-closed,
dual-closed class of Higgs lift delta-matroids that arise from lattice paths.
It follows from results of Bouchet that all delta-matroids can be obtained from
full Higgs lift delta-matroids by removing certain feasible sets; to address
which feasible sets can be removed, we give an excluded-minor characterization
of delta-matroids within the more general structure of set systems. Many of
these excluded minors occur again when we characterize the delta-matroids in
which the collection of feasible sets is the union of the collections of bases
of matroids of different ranks, and yet again when we require those matroids to
have special properties, such as being paving.
