Abstract: A system and method for identifying captured written data associated with a writing surface using a pen-based computing system are described. In one embodiment, a series of writing surfaces, such as notebooks, are produced, each including a plurality of pages that have an encoded pattern. In an embodiment, each writing surface is also associated with an identifier recognizable by a smart pen or other data capture device. When the smart pen captures written data from a writing surface, the smart pen determines whether the pen-based computing system includes stored written data previously captured from a writing surface having the same encoded pattern as the writing surface from which written data is currently being captured.