[I--] = 4 = Unknown Device = that big map thing that got activated
filled circle = objective complete
hollow circle = next objective
This is a set of instructions. FOR HUMANS TO FOLLOW.
I think this is a set of instructions describing what the probes do, the bottom hatched circle is a searched dimension and the top hatched circle is an unsearched dimension. The probe and UA check merope and the mystery system in each dimension and then the UL propagates (or links) them to the next dimension.
Alternatively the hatched circle is the thargoids home dimension (witchspace?) but that doesn't account for the filled/unfilled, circle. the flower v shapes are thargoid ships that assist in the operation.
But none of that is explains the 2 spiral armed galaxy that is in the structure.