With help from Google, I think I've answered my own question; according to the NZ Securities Commission, disclosure must be made when:
* a person becomes a substantial security holder (at the 5% threshold);
* whenever a shareholding changes by 1%;
* when there is a change in the nature of any relevant interest held by a substantial security holder; and
* when a person ceases to be a substantial security holder.
http://www.newsecuritieslaw.govt.nz/...er-disclosure/
This would indicate that all such disclosures for NZO should have already been made?
Bob C