5.1 The Version Tree

Each time you revise and check in an element, ClearCase creates a new version of the element in the VOB. Throughout this part of the book, this linear progression has been illustrated with a graphic similar to Figure 19.

Figure 19 Linear Progression of Versions

ClearCase can organize the different versions of an element in a VOB into a version tree. Like any tree, a version tree has branches. Each branch represents an independent line of development. Changes on one branch do not affect other branches until you merge. In Figure 20, main, pat_usability, and db_optimize are branches being used to develop different releases of the file element prog.c concurrently.

Figure 20 Version Tree of a File Element

Under the Hood: The Initial Version on a Subbranch

When you create a subbranch for an element, which is any branch below the main branch, the initial version contains the same data as the version from which you start the branch (Figure 21). (The initial version on the main branch contains no data. For more information, see Excluding Elements.)

Figure 21 The Initial Version on a Subbranch