The answer is in the question: A protocol study of intelligent help

Thirty advisory interactions between computer system ‘help desk’ consultants and their clients were transcribed and analysed as part of a project to determine the behavioural requirements for intelligent on-line help facilities. An interesting property of these interactions is that the advice was frequently modified in response to verification requests: questions (often syntactically implicit) which contain presuppositional statements that are partial answers to the asserted query. Designs for intelligent help facilities might exploit this finding by supporting the verification strategy and attempting to extract and use the presupposed statements in these questions to generate advice.