Interrelation of the Partzufim — in the chain of development and through clothing one another.
The general rule of Partzuf-pair interrelation: every upper-lower Partzuf relationship has both a chain of development and a clothing relation. Both must be considered.
Op. 109 closes the A"A unit (Op. 90–109) by stating the general rule that runs through the rest of the book. Every upper-lower Partzuf relationship — Atik Yomin-A"A, A"A-Abba/Imma, Abba/Imma-Zeir Anpin (Z"A), Z"A-Nukva — operates in two modes: chain of development (hishtalshelut) and clothing (hitlabshut). Both modes are real; both must be investigated.
Chain of development (hishtalshelut). The lower Partzuf develops from the upper Partzuf. Op. 93 (Z"A derives from A"A) is one specific instance. The chain is the cosmogonic-causal relation: the lower's existence and operational identity come from the upper.
Clothing (hitlabshut). The lower Partzuf wraps around the upper Partzuf, or vice versa, with the operational consequence that one's interior is the other's exterior (or vice versa). Op. 96 (Atik clothes in A"A) is one specific instance.
The rule is that both modes are simultaneously present. When you investigate any Partzuf-pair, the operational reality is both the chain of development and the clothing. To investigate only one mode is to miss the other half of the structural truth.
This is the methodological apex of Klach's investigation. Op. 17 (Sefirah and Partzuf as two pathways) and Op. 8 (contradictory likenesses) prepared the both-modes framework; Op. 109 generalises it to every Partzuf-pair relation.
Op. 110 will apply Op. 109 directly to the Atik-A"A pair as the paradigm case. Op. 111–114 (Abba and Imma's structure) operates under Op. 109. Every later named-Partzuf chapter operates under the rule.