A B-liner diagram is a hierarchy. Brackets enclose decompositions. The diagram flows from the general to the specific, one level at a time. The root or most general concept is the leftmost statement. The diagram starts at the left and proceeds to the right. It allows you to describe something one level at a time.

For example, below is a diagram for the process of making a peanut butter and jelly sandwich. Notice how the diagram gets more specific with each level.

The above diagram shows the general layout of all B-liner diagrams. The diagram makes the overall structure, as well as the details, visible at a glance.

This type of organization also makes a diagram easier to understand. When a diagram is read one level at a time, the reader doesn't become overwhelmed by the details.

These diagrams are called Warnier/Orr diagrams.