Nis a port of the excellent Apache Jakarta project. It is a very simple, easy to learn and extensible template engine.
Due to the lack of releases, support and bug fixes on the original port, the Castle Team decided to fork the project, bringing it to our code repository, fixing the bugs and improving it with more features.
The first thing you need to read about Nis not even on this web site. You can find on the original Velocity web site.
The following pages explain more about NVelocity, the bugs fixed and improvements made.