Although great progress has been made in the development of visual languages, little attention has been paid to how diagrams in such languages should be entered into computers. This issue will have a great impact, however, on users' acceptance of visual languages. We present an analysis of the features of visual languages influencing diagram entry, and also the results of an experiment comparing users' performance on different types of diagram editors. This data is then used to suggest design guidelines for usable visual language front ends. 1: Introduction Visual notations for programs have been in existence virtually from the invention of programming, and visual languages that can be interpreted by computers have been in existence for the last 15-20 years. Since that time, the visual notations have become more complex as language designers have become more aware of the power of visual notations and as available technology has become more sophisticated. In contrast to these advances,...

The programming walkthrough is a method for assessing how easy or hard...