ARNOLD is an application for scheduling recurring meetings. The inspiration came from a group of friends that used to meet every week, but with the progress of personal and professional lives found it hard to keep having these meetings.
Obviously, the friends also used to enjoy the wonderful action movies of the 80's starring Arnold Schwarzenegger, leading to the naming of this magnificent piece of sofware.
At this moment, not much of the application has actually been designed or even defined.
Have a look at the open issues tagged with design to see what the latest ideas are and see the features/ folder for what has been specified so far.
Whatever the requirements turn out to be, this project is meant to be a bit of a sandbox for development. If someone would like to master a new programming language or approach, why not use it to write another ARNOLD-implementation? As a consequence, there might be several different versions of the program in the future. Making sure all past and future implementations will be compatible with each other should therefore be part of the design criteria.
You are welcome to leave any ideas, suggestions, complaints or bug reports you might have. Just open an issue, and we'll get the discussion going. Of course, adding a pull request with your feature or fix will greatly enhance the chance of it ever getting integrated.