This page explains grid reference systems, with specific emphasis on New Zealand. If you are interested in making a grid reference system for your map read this page and then see:
What is a grid reference system?
A grid reference system is a simplified grid used for a map area to make reporting and looking up coordinates easier.
One thing that has always frustrated me in ArcGIS is selecting coordinate systems. ArcGIS does feature a “favourites” options for coordinate systems but this only appears in a couple of dialog boxes.
The solution: Just copy and paste the coordinate system files to the same folder as all your coordinate systems.
On my computer the path was C:\Program FIles (x86)\ArcGIS\Desktop10.0\Coordinate Systems.
Now when I browse they appear right under coordinate systems.