Each participant has access to a Logitech I/O digital pen to records the handwriting notes. The pen stores the time stamped x-y coordinates of any pen strokes made on special paper that contains an embedded 2D bar code. The pen strokes are then downloaded to the auxiliary capture PC as xml files for subsequent processing. The pens are synchronized to the auxiliary capture PC at the beginning and end of each meeting. Since they are not connected to the synchronization equipment during the meeting, precise calibration cannot be guaranteed. In practice, the pens' internal clocks do not drift by more than a few seconds during each meeting, resulting in sufficiently calibrated data.