A weigh ticket can target one of three things:
Animal — one tagged animal across the scale.
Lot — a whole lot weighed together.
Pen group — a pen of animals weighed as a batch.
The subject decides which record the ticket attaches to and how its weight gets used. A lot weigh feeds the lot's aggregate weight; an animal weigh records that one animal's weight.
Technical section
Data model, API, and internals — visible to developers.