Dependency relationships in composite baselines of ordinary components

In a composite baseline of a component that has a root directory in a VOB (an ordinary component), a tightly coupled relationship exists between components as shown in the following figure.
Figure 1. Tightly coupled relationship between baselines

Baselines A.BL1 and C.BL3 are aligned vertically, connected by a solid line.

A.BL1 is a baseline on component A that groups directory and file elements and is also a composite baseline that selects baseline C.BL3 of component C. Baseline C.BL3 is a member of composite baseline A.BL1. Composite baseline A.BL1 depends on the member baseline C.BL3.

A change to the baseline in component A could be caused by a change in the configuration of component A (that is, a member being added or dropped) or by a new baseline in component C. This type of component arrangement is tightly coupled, for example, if code in component A depends on code in component C.

In the tightly coupled relationship, the composite baseline A.BL1 fulfills two roles: selecting baselines from other components and identifying a set of versions in its component. Determining the reason for making a new descendant of this type of composite baseline is expensive (in terms of performance). Using a composite baseline that has tightly coupled relationships imposes configuration restrictions. For example, you may only be able to do an advanced rebase operation.