A Modal Model of Versions

Alan Dix [1], Tom Rodden [2] and Ian Sommerville [2]

  1. School of Computing, Staffordshire University, Stafford, UK.
    email: alan@hcibook.com
  2. Department of Computing, Lancaster University, Lancaster, UK.
    email: tam@comp.lancs.ac.uk is@comp.lancs.ac.uk

Paper presented at the BCS-FACS Workshop on "Formal Aspects of the Human Computer Interface", Sheffield, September 1996. Proceedings originally published as part of the Electronic Workshops in Computing series (originally Springer, now maintained by the BCS)

An extended version of this paper is also available as:
A. Dix, T. Rodden and I. Sommerville (1997).
Modelling Versions in Collaborative Work. IEE Proceedings - Software Engineering, 144(4) pp. 195-205.
abstract || full paper (compressed postscript, 730K) || full paper (PDF, 88K)


Version management is usually associated with heavily controlled domains such as software engineering and traditional engineering design. Several systems embodying ideas of versioning have been developed or proposed in the CSCW (computer-supported cooperative work) arena where the emphasis is less on control and more on supporting dynamic group activities. We need to understand the relationship between these areas with sometimes similar, but often radically different, ideas of the word version. In this paper, we lay the groundwork for this by developing a generic model of versioning. We do not model a specific version management policy or system, but seek to capture the idea of a version whether electronic or physical, implicit or explicitly stored. Starting from the definition that "a version is the value of an entity in a context", we come naturally to a modal model of versions.

Alan Dix 28th September 1996