A method of recording receipt of an item, the item comprising a product contained in a package, the package comprising an interface surface having disposed thereon coded data indicative of an identity of the item and of coordinates of a plurality of locations of the interface surface. The method includes the steps of: marking the interface surface using an optically imaging pen having a marking nib; sensing the coded data in the vicinity of the pen; generating indicating data using the sensed coded data, the indicating data including data regarding the identity of the item and positions of the pen relative to the interface surface; and transmitting the indicating data to a computer system.