Why Some RX-78 Variants Aren’t Counted as “Xth Unit” Gunpla in the 1st–8th System

The article explains that Amuro’s RX-78-2 is tied to a 1st–8th “unit number” setup, but certain RX-78 variants like “Alex” and “GP” aren’t counted as “Xth units.” It outlines the reasoning behind that distinction.