Hi, The use I have is to implement binary messages that are user through protocol stacks. When sending a message, lower layers add usualy headers and trailers to payload comming from the upper layer. When receiveing a message, lower layers extract its corresponding headers and trailers before passing the payload to the upper layer. I'm thinking in generalizing the stream or archive concept, so we could in addition to been able to read from the begining and write at the end, been also able to read from the end and write from the begining; a kind of bidirectional stream or archive. I was thinking in namming the concept "frame", as frames are usualy composed of header, payload and trailer. Do you have other namming sugestion? Could this concept have any interest for Boost? Please, let me know if there is already someting on Boost or the standard library that could help me. Best, _____________________ Vicente Juan Botet Escribá