The reference on "composite Baselines" is: "Best practices for using composite baselines in UCM".
Introduced in ClearCase v2002, composite baselines are a mechanism for grouping baselines into a collection. One baseline is designated as the composite, and other baselines become members of the composite
![composite baselines](https://i.stack.imgur.com/wMYzm.jpg)
You do not necessarily have to use composite baselines when you have multiple components, but:
If you want to remember the set of baselines existing at a given point on your Stream, then having a rootless component able to record of the baseline of its member is useful.
In theory, you can have "composites of composites":
![multiple levels](https://i.stack.imgur.com/u10V2.jpg)
I wouldn't recommended it, though, because of the "parasite baselines (explained briefly here and here)
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