In a non-configurational language such as German, which features argument composition, heads combine with complements that are not their own arguments but rather those of a predicate they compose with, i.e., they need to cater for unknown raised arguments by means of underspecified valence lists.
the identity of the inherited arguments is not known, so any XP present in the chart, however inflected, can sneak into these underspecified lists, to be ruled out, in the majority of cases, only when a significantly larger structure has been built.