Suppose answering a particular question type involves typing some particularly complex syntax. Then the educational goals are better served if we do not penalise simple syntax errors. Here are two examples:

1. Suppose we want to create a version of the short answer question type that automatically spell check's the student's answer, so their answer is only marked after they have corrected any spelling mistakes.

2. Süreç Özcan's JUnit question type. Here the student's goal is to write some code that passes a set of unit tests given by the teacher. In this case, we may want the option to let the student verify that the code they have typed compiles without errors before they have to submit it for grading.

There was a vague attempt to implement this once before (for example, there is an QUESTION_EVENTVALIDATE constant defined at the top of lib/questionlib.php) but it never went very far.