MAYAStock is tracked under Catalogue then Inventory, when your plan includes this module. Not to be confused with the Treasury inventory, which counts cash.
A catalogue item marked as stockable becomes a stock item; a service has no stock. Each entity can have a default warehouse: without one, receipts and sales go to an unassigned line.
An outgoing movement is judged on the warehouse it leaves from, not on the total: MAYA refuses it if that warehouse does not have enough, and says what is available. Cancelling a movement reverses it once only.
Counting is done in three steps: open, count, validate. Counting freezes the theoretical stock at that moment; on validation, a line that has moved since is named and not applied, and differences go through movements, never below zero.
A purchase receipt brings stock in (if this setting is on, which it is to start with), and a sales invoice takes it out of the default warehouse, never below zero. Replenishment proposes orders, it never places one on its own.
PlansIncluded in every plan.