Arc is made up of a number of directories (folders) representing the different parts of the application.
Root - This is the base of the application and entry point for access.
+ App - App contains all of the features and functions for modules and used to expand the system.
+ Addons - This folder contains page extentions that are rendered as addons to module pages allowing for extended features. These can be things like adding a nick name field to the user details page or customer information depending on how you intend to use the system. The folders inside the addons folder must start with the module name then the view its extending for example: Arc -> Userdetails -> CRMUser. See addons for more information.