Packet switching node in a communication system includes apparatus for receiving incoming information packets or frames which contain header portions with formatting control blocks. Information in the frame's header contains frame alteration commands for modifying the information in the frame. The modifications include adding new information, deleting information, and overlaying information. Decoders and control devices in an alteration engine interpret the commands and apply the modifications to the frame data. Common and standard data patterns are stored for insertion or overlaying to conserve data packet space.