Production processes differ by structure and the nature of flow of work-in-process through that structure.
There are four basic types of work flows, which are referred to as “A”, “V”, “T”, and “I”.
This taxonomy is based on the graphical representation of their respective flows.
The flow of work through production has a direct impact on exploiting the constraint and subordinating non-constraints.
Source: Oded Cohen and Jelena Fedurko, Theory of Constraints Fundamentals, 2012