Describes the Data Reconfiguration Service (DRS) now being implemented at MIT, UCLA, UCSB and RAND for the ARPA computing network. In this nationwide experimental network, widely separated computers of different makes, models, sizes, speeds, hardware, and software are interconnected via store-and-forward switching by small special-purpose computers called Interface Message Processors that route traffic adaptively over leased lines. Participants can remotely access programs, data, and unique hardware facilities anywhere in the system. The DRS is designed to overcome the hardware and software incompatibilities by automatically performing needed data manipulations, such as converting character sets and graphic codes, adding or deleting messages, packing or unpacking repeated symbol strings, inserting message counters and flags, transposing data fields, and reformatting files. The syntax and semantics of the network connection module and the "Form Machine" are described. The Form Machine is a module that accepts and applies the definitions of data reconfigurations (forms).