No force org slot means that a unit, mostly under specific conditions, does not take up a force orginization slot.
If you take an arcon, the court of the arcon does not take up an elite slot even though they are in the elite section.
If you had no arcon, they would take up the slot.
this is for list building under normal play (not unbound) where you are limited in choices. It is a way to get extra models without having to give up a spot in the roster.
hope that helps
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