Electronic pen for interacting with substrate

An electronic pen for interacting with a substrate having a pattern of coded data printed thereon, said pen comprising:

• an infrared light source for illuminating an area of the substrate;
• an image sensor for imaging at least some of the coded data illuminated in said area when the pen is used to interact with the substrate;
• a force sensor configured to sense interaction between the pen and the substrate;
• a processing system configured for:
• determining digital ink from the imaged coded data, said digital ink comprising a sequence of pen positions representing handwritten information;
• storing the digital ink in a memory buffer;
• determining, from the imaged coded data, whether said pen is positioned within a predetermined functional zone of said substrate;
• and
• initiating a response in said pen in the event that the pen is positioned within the predetermined functional zone,
• wherein the response is initiated without reference to a remote computer system.