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.