  Software has always been considered as malleable. Changes to software
requirements are inevitable during the development process. Despite many
software engineering advances over several decades, requirements changes are a
source of project risk, particularly when businesses and technologies are
evolving rapidly. Although effectively managing requirements changes is a
critical aspect of software engineering, conceptions of requirements change in
the literature and approaches to their management in practice still seem
rudimentary. The overall goal of this study is to better understand the process
of requirements change management. We present findings from an exploratory case
study of requirements change management in a globally distributed setting. In
this context we noted a contrast with the traditional models of requirements
change. In theory, change control policies and formal processes are considered
as a natural strategy to deal with requirements changes. Yet we observed that
"informal requirements changes" (InfRc) were pervasive and unavoidable. Our
results reveal an equally 'natural' informal change management process that is
required to handle InfRc in parallel. We present a novel model of requirements
change which, we argue, better represents the phenomenon and more realistically
incorporates both the informal and formal types of change.
