> Is Overflow (PL) going to communicate with the BL through InputStream and > OutputStream? If could, but it doesn't have to. Let me explain what those are. An InputStream node takes a string (generally a file name) as input, opens it and returns a C++ ifstream that can be used by other nodes to read info. The same for OutputStream. I think the best way to communicate is simply via function calls: the BL calls Overflow functions and get the result. Jean-Marc -- Jean-Marc Valin Universite de Sherbrooke - Genie Electrique valj01 at gel.usherb.ca