Paper.JS Hierarchy - Stetson-Team-Alpha/paper.js GitHub Wiki

PaperJS Hierarchy
PaperScope – Holds an array of projects
Project – Also known as a document. Top level object that holds all of the layers contained in the scene graph. (Level that we want to be importing/exporting). 
Layer - Extends Group which contains an array of objects called children. 
Item – Base class from which the different project item types such as Path, Group, Raster are inherited from.