Yet, it is very legit to set an array to size zero on the X-axis, and minimum 1 on the other two.
The purpose is this.
Add a new index (on X) based on a loop, so you end up with an array with a width = a loopindex. Not one less, not one index more.
So .....
Some group
Some condition
____ Array > action > Set size ... (0,1,1)
Some loop
____ Array > action > Push (front) < makes a new X-axis element on X = zero
____ Array > Set at XYZ ... <--- With X = ZERO to fill values on Y or Z .. example = at (0,1)
or
Some group
Some condition
____ Array > action > Set size ... (0,1,1)
Some loop
____ Array > action > Push (back) < makes a new X-axis element on the end of the X-axis
____ Array > Set at XYZ ... <--- With X = Array.width - 1 ... example = at (Array.width - 1,1)