NZBC, Decree Establishing Criteria for Clerical Dress, October 1994.
The criteria for clerical dress be:
1) identifiable as clerics;
2) appropriate to the occasion;
It is left to the Diocesan Bishop to be more specific if he judges it appropriate.
NZBC, October 1994, Gen. Decr., Code of Canon Law Annotated (Montréal: Wilson & Lafleur Limitée, 2004): 1714.