Base Folder

Base Folder include the core files.
You can see that as Harmony framework.

Customization

Generally yuou should not change the files in this folder
unless you know what is going there and you want to custom it. See more Contributing section if you want to improve Harmony Base Folder :).

Inside base you can found Features folder:

features

Features include all the core features that use in your application, such as error handler, global spinner logic etc ..