During the development of the first ISO software ergonomic standards, the question of how conformance should be stated became a major issue. Since user interfaces are based on many design variables (e.g., types of users, tasks, system components, environmental factors), it is rarely possible to state absolute requirements. Most previously published information concerning user interface design was in the form of guidance. However, ISO standards must be expressed in terms of requirements and recommendations, i.e., “shall” or “should” statements. In addition, requirements are the only type of statements that are considered “normative” in terms of conformance to the standard. In other words, a person claiming conformance to an ISO standards need only meet the stated requirements and does not need to meet the recommendations.
Presenters: James R. Williams (Synergetic Applications) and Thomas Geis (ProContext Consulting GmbH)
Full paper: http://www.ingentaconnect.com/content/hfes/hfproc/2008/00000052/00000006/art00005?crawler=true