Abstract
Indexing P arguments on bivalent predicates is often considered more restricted and less often obligatory than A indexing. However, differential A indexing, i.e., the absence versus the presence of an index referring to the A argument role, is not uncommon either: usually present A indexes can be omitted in particular discourse settings. However, differential A indexing has been a Cinderella subject in the typological study of differential marking, as opposed to differential P indexing or differential A flagging. This paper scrutinizes various cases of both differential A and P indexing and examines structural and functional differences and similarities. It will be shown that exploring differential indexing helps to understand how indexing in general is linked to referential prominence which surfaces as factors such as identifiability, animacy or topicality. Cases where indexing is particularly sensitive to referential prominence, and where it thus is employed only if the referent fulfills certain criteria, bring out the fact that A and P indexing have a common purpose, namely tracking referents through discourse. In this context, the paper also points out that differential A indexing presents an exception from generalizations concerning the amount of material in coding asymmetries.