Different degrees of connection of male and female in different Partzufim.
Partzufim are ordered by the degree of intrinsic male-female union: from Atik Yomin's one body at the top through the more-distinct couplings of A"A, AvI, ZuN at the operational levels.
Op. 73 closes the Partzufim unit by ordering the four named Partzufim of Atzilut by the degree of intrinsic male-female union. The ordering is structural — it reflects each Partzuf's location in the cosmic-anatomical hierarchy.
At the top: Atik. M and F are literally one body (Op. 75 will develop this). Maximum union; minimum distinction.
Next: Arich Anpin. M and F are present as aspects of A"A but operate within A"A's single body, not as distinct partners (the dechura ve-nukva of A"A). Less union than Atik but still highly integrated.
Next: Abba and Imma. M and F are now distinct partners — Abba and Imma are two separate Partzufim, but their coupling is constant (Op. 113). Distinct but constantly joined.
At the bottom: Zeir Anpin (Z"A) and Nukva. M and F are distinct partners with variable coupling. Z"A and Nukva couple in different modes at different times; the cycle's deed-dependent operational variability operates at this level.
The ordering is also temporal-architectural. Higher Partzufim are more concealed (their union is more intrinsic, not visible at the operational surface); lower Partzufim are more revealed (their union is operationally visible). The cycle's operational deeds occur at the Z"A-Nukva level because this is the level at which male-female differentiation is most fully expressed.
The named-Partzuf walk (Op. 74 onward) operates through this hierarchy. Atik first (Op. 74–77); Arich Anpin (Op. 90–95); Abba and Imma (Op. 110–114); Z"A and Nukva (Op. 115–138). Each unit's male-female architecture follows Op. 73's framework.