General principles

The main differences with respect to UD are the following:

UD relations that are not used in SUD: nsubj, csubj, obj, iobj, obl, xcomp, ccomp, amod, nmod, nummod, advmod, acl, advcl, aux, cop, case, mark. These 17 relations are replaced by three major relations in SUD – subj, comp, mod (subject, complement, modifier) – with possible sub-relations, in addition to the general udep (underspecified dependency) to a more marginal extent.