i dont get it or the help file is inconclusive !!
AXIS_1_VECTOR, AXIS_2_VECTOR, Size_1, Size_2
referring to "size"
"There is no point in using circular with linear area lights or area lights
which have a 2x2 size."
.. .
.. . that's already circular.
suggesting "size" = n lights.
and the vector length = array dimensions
so I'm still not sure, also it to alludes to adaptive n = n lights.