Optional catch-all — segment [[...region]] = ["andaman-nicobar","great-nicobar"]
Great Nicobar
Largest island in the Nicobar chain; primary forest still dominant.
On the next outbound RSC fetch, this optional catch-all encodes as ["region", "andaman-nicobar/great-nicobar", "oc"] when populated, or just disappears from the path when empty. The "oc" type distinguishes it from a required catch-all [...region] (which would be "c").