MULTI-LEVEL OPTICAL MARK READING THAT USES AN UNAMBIGUOUS SYMBOLOGY OF MARKS TO FILL INTO RESPONSE BUBBLES

One or more response bubbles are used on a scannable form to be read by a scanning system. An unambiguous symbology of marks is defined to fill into each response bubble, thereby allowing at least one of a plurality of different non-empty intended responses having different output values to be entered into each response bubble. One or more response bubbles are provided on the scannable form to be filled in according to the defined symbology of unambiguous marks. A filled in form is scanned with the scanning system and an image of the scanned form is processed by identifying pixels associated with each response bubble, interpreting the pixels associated with each response bubble to define a raw score according to the defined unambiguous symbology of marks used to mark each response bubble, translating the raw score for each response bubble into one of the plurality of different intended non-empty responses, and outputting the value of the non-empty response for each response bubble. Different output values have different meanings.