Our advice
OT or WBS task flowchart

By its very nature, an OT requires that all relationships between tasks be established on a schematic. To obtain a relationship, a code can be defined and assigned to the elements. It's best to keep the code simple, to show how the project is structured.

The TO becomes the common basis for defining all the project's major deliverables, as well as for estimating costs. The level of detail depends on the complexity of the project, bearing in mind that the lowest level in a TO is the component work package of a deliverable. The sum of the costs to complete the activities within a job is the cost of the deliverable. The sum of all deliverables is the total project cost.

Don't forget that building a task organization chart...