An Endpoint is the last place your Refuse ends up before it is combined with the Refuse from other program divisions within your organization, or before it is taken away by your Hauler. If you have divided up your program divisions by building, then typically the commercial container collects Refuse at the "back of the building" so that it can be easily accessed when it is picked up to be transported, this will be your Endpoint.
In the event that you have divided your program divisions into areas smaller than an entire building, then your Endpoint will likely be the transportation cart (or even a centralized station). For example, if you have divided your program division up by floors in an office building, your Endpoint will likely be the transportation cart for that floor. When conducting a Composition Audit, you should audit this Refuse prior to it being combined with the Refuse from other floors.