What is user area?
User areas is a way to divide a drawing area on an application level. User areas are of no meaning to the pen. It is just a way to mark specific areas within the drawing area in order for the application to handle them in a specific way. If, for example, a form has name, address and phone number on it, then you mark the name with one user area, the address with another and the phone number with a third user area. The application can then be enabled to to collect the strokes from a specific area.
FDT, Paper SDK