  Software process models must change continuously in order to remain
consistent over time with the reality they represent, as well as relevant to
the task they are intended for. Performing these changes in a sound and disci-
plined fashion requires software process model evolution to be understood and
controlled. The current situation can be characterized by a lack of
understanding of software process model evolution and, in consequence, by a
lack of systematic support for evolving software process models in
organizations. This paper presents an analysis of the evolution of a large
software process standard, namely, the process standard for the German Federal
Government (V-Modell(R) XT). The analysis was performed with the Evolyzer tool
suite, and is based on the complete history of over 600 versions that have been
created during the development and maintenance of the standard. The analysis
reveals similarities and differences between process evolution and empirical
findings in the area of software system evolution. These findings provide hints
on how to better manage process model evolution in the future.
