A digital pen and paper technology from the Anoto Group AB, Lund, Sweden.  Anoto uses regular paper imprinted with a dot grid that is almost invisible.  The dot grid is coded so that when traced with an Anoto-enabled pen, which also discharges ink like any ballpoint pen, the pen's built-in camera detects the unique dot pattern and records the handwriting or drawing.  Via wireless or USB, the pen transmits either ASCII text or images to a receiving device.  See 
digital pen.
The Anoto Grid
The dot pattern on the paper is a measurement scale for the pen strokes.  For pens with audio recording, it also provides a time line for synchronizing the hand-written material with the recorded lecture.