A sensing device for enabling interaction between a computer and a form printed on a surface. The form includes one or more first viewable information zones relating to one or more available commands and one or more second viewable information zones relating to one or more objects. The form also includes coded data indicative of an identity of the form and of at least one reference point of the form, the coded data comprising a plurality of substantially undifferentiated marks positioned relative to a set of predetermined nominal mark positions. The sensing device is adapted to sense the coded data of a form when placed in an operative position relative to the form, the sensing device further being adapted to generate indicating data indicative of a stroke of part of the sensing device on or relative to said form and to transmit the indicating data to the computer. The indicating data generated by the sensing device and transmitted to the computer allows the computer to determine if said stroke substantially links one or more of said first viewable information zones with one or more of said second viewable information zones.