A system enabling a user to initiate a requested action via a printed substrate. The system comprises: a printed substrate comprising user information and a position-coding pattern; an optically imaging pen comprising a nib, an image sensor and a processor; and a computer system for identifying and initiating the requested action. The processor is configured for decoding the imaged position-coding pattern, determining a first position using the decoded position-coding pattern, and determining a second position using the first position. The second position is different than the first position, and is used by the computer system to identify the requested action.