In Modern Written Arabic, at least three different groups of constructions can be found in which
nonlocal dependencies seem to play an important role. Relative clauses and adjective attributes,
which can be seen as a mere variant of relative clauses, often contain a resumptive pronoun
referring to the modified NP. Extraposed NPs have nominative or accusative case regardless of their
relationship to the phrase they are extracted from. As it is the case with relative clauses and
adjectives, comment sentences often have a resumptive pronoun referring to the extraposed NP. Since
the case of extraposed NPs and of relative pronouns entirely depends on external factors, the REL
feature seems appropriate for the analysis of relative clauses and adjectives. On the other hand,
for the extraposition of other phrases and for wh-questions, the classical HPSG analyses based on
the SLASH and QUE features can directly be applied to Modern Written Arabic.