Acronym for Unique Domain Authentication ID.
An¹ UDAI applies to every .nz DomainName. It is a unique identifier issued at the time of registration of a DomainName under the New Zealand SRS (Shared Registry System).
To transfer a Domain Name from one registrar to another, the UDAI must be supplied to the gaining registrar.
If you have lost your UDAI, you can request your current registrar to generate you a new one.
1 An or A ? Is it a U-D-A-I, or an oo-die ?
Resources:
http://dnc.org.nz/story/common-terms#udai
One page links to UDAI: