A Global location Number (GLN) is a thirteen-digit number that is used to identify physical locations such as factories, farms, orchards, warehouses etc.
It has the same format as GTIN but the prefix (for GLN's allocated in NZ) is GS1 New Zealand's and the GLNs are issued by GS1.
Note that an NZBN (New Zealand Business Number) is a type of GLN and is used to identify your business entity in GS1s system.
The Rules for allocating GLNs are at
http://www.gs1.org/1/glnrules/
For further information refer to the NPC area of this Support Centre.