A pen is a real spot in the yard where animals are held. Tally tracks pens so staff always know where a consignment is — from intake through pickup.
Each pen has:
a code (unique in your barn) and an optional location label,
a capacity — the recommended number of head it holds,
an optional species it's set up for.
When animals are received, they're assigned to a pen. That pen assignment records the head count and follows the consignment until the animals are released at loadout.
Capacity is a soft limit — Tally will flag an over-capacity pen rather than block you, because real yards sometimes crowd a pen during a busy intake.
Admin section
Permissions, locking rules, and setup — visible to admins.
Technical section
Data model, API, and internals — visible to developers.