As per the subject above, are they?
I realise cars issued with plates prior to 1988 were issued with these as standard.
The reason I ask is I saw a '88 Toyota Corolla stationwagon today that had a recent number plate (FLN7XX - i have removed the last two digits just in case) that was exactly as above, sliver letters on a matt black background.
I didn't get a good look at it (since I was driving) so couldn't tell if it was home made or not.
I have done a quick search online, and found the following forum that has links/exerts to/from the Transport (Vehicle and Driver Registration and Licensing) Act.
http://www.vask.org.nz/index.php/topic,8746.0.html
What are your views, looking at the email that one of the forum members was sent, it does look like either option is legal.