Prefix and Region and Island name (not required all fields)
Region format: *Z-001* (for example: Z-0 or Z or 01 or 001)
Island name format: *name* (for example Polelum isl: to put polel or lelu or elum)

you want to search islands from Z region of Poland (to put: Prefix 161 Region z)
you don't know full island name Polelum from Poland (to put: Prefix 161 Island name po)