Instructions for operating a control panel were presented in five different formats: flowchart, logical tree, yes/no tree, decision table, and list. Subjects had to choose one out of eight buttons, depending on the settings of the control panel. The results show that the decision table resulted in more errors, and that both the decision table and the list took longer than the three other formats, which did not show mutual differences. It turned out that the subjects valued most the format they had been using, except for those who had worked with the list. It is suggested that the users' ease of orientation for a diagram's format, both during reading and after "switching" between equipment and instructional text, explains the differences between the formats.