Patent ID: 7243122

Claim:
A method for communicating between computers interconnected by a communications network, the method comprising the steps of: (a) receiving, at a deriving computer, a request from a client computer for transmission to the client of a user-selected version of a target file, the target file having particular informational content independent of its embodiment in a particular version; (b) responsive to receiving the request in step (a), transmitting from the deriving computer to a server computer distinct from the deriving computer a request for transmission to the deriving computer of a materialized parent file from which the user-selected version may be derived by conversion, the materialized parent file being stored on the server computer; (c) at the deriving computer, deriving by conversion the user-selected version from the materialized file, the materialized file having a first file format, the user-selected version derived by conversion having a second file format different from the first file format; and (d) transmitting, from the deriving computer to the client computer, the user-selected version.