There are three different possessive-like constructions: s, e, and e s.

s alone marks inalienable possession:
aʼ su mpaʼ "my penis"
(possessor _ possessed)

e alone marks alienable possession:
brö e aʼ "my wall"
(possessed _ possessor)
And also some other things.

e s marks descriptive properties, locatives, and that sort of thing - the possessed thing is not really a concrete object, like a brick or a penis, but neither is it easily separable or removed from the thing. This is probably an innovation.
brö e s të "the inside of the walls"
(possessor _ possessed)

However! modified e modifier, not modifier e modified.