A system for enabling user interaction with computer software which
includes a printer and sensing device. The printer receives print data
and prints a form by printing information related to at least one text
field coincident with coded data indicative of the text field, receiving
indicating data from the sensing device and transferring the indicating
data to a computer system to allow the interaction to be interpreted. The
sensing device has an image sensor for capturing images of the coded data
when moved relative to the text field, and a processor which identifies
the coded data from the captured images, determines an orientation and
position, within the captured images, of the coded data, decodes the
coded data, and generates the indicating data using the decoded coded
data and the determined orientation and position.