An operation-costing system is a hybrid-costing system applied to batches of similar, but not identical, products.
Each batch of products is often a variation of a single design, and it proceeds through a sequence of operations.
Within each operation, all product units are treated exactly alike,
using identical amounts of the operation’s resources.
A key point in the operation system is that each batch does not necessarily move through the same operations as other batches.
Batches are also called production runs.