noun incorporation in Nahuatl

[David Eddyshaw]

Quite often in general linguistic discussions of polysynthesis I've
come across the assertion that incorporated objects in Nahuatl can be
referential (ie. are active in discourse, can be picked up by pronouns
etc). For the life of me I can't see this; as far as I can see in fact,
for a noun stem to be incorporated into a verb as object it actually
must _not_ refer to any particular entity. Am I just wrong about this?
Is it something in which Classical Nahuatl differs from some modern
dialects?

David Eddyshaw