Abstract
It has been suggested that task analysis of humancomputer interaction could be enhanced by distinguishing 'work' actions, which perform transformations in the work domain, from preparatory or 'enabling' actions. The work/ enabling distinction is discussed alongside related ideas in work study and HCI. This study investigated methodological implications of applying the distinction to complex systems, using videotaped use of geographic information systems (GIS) in real workplaces. The study supports the prescriptive potential of the work/enabling distinction in system design and comparison, although methodological issues include the need for extra categories of behaviour to account for all interaction.