This Recommendation describes howinteractions should take place between the user and the system from alogical viewpoint. It describes how an effective man-machine interface should appear to the user when utilizing thecapabilities of VDTs as described in Recommendation Z.322. This Recommendation supersedes RecommendationsZ.311-Z.317 for interfaces based on VDTs, referencing parts of them where appropriate. Specific human factorguidelines are included within the appropriate divisions of the text.