Abstract
After defining more precisely the notions of task, activity and error, this paper distinguishes different representations of the task: prescribed; supposed prescribed; projected; really carried out task. The deviations between these types of representations are then considered as aids for error analysis and the information which can be extracted of them are shown from some examples. Also indicated is the benefit the study of error recovery can bring to work analysis. Finally how can the defined frame of analysis be exploited together with the different ways it can suggest for the error analysis is examined.