The X224 data files are generated by the dbn_async.pl extension. The async extension reads data from an asynchronous communications port and builds a file for each 20 seconds of data. The files contain the X.224 CCB header and data. The extension was written to receive data from the OSO via an X.25 line. The X224 raw files are then passed to the dbn_x224.pl extension which converts the 20 seconds of data into individual WMO files. The x224 extension validates the CCB header and WMO message header. Segmented messages are rebuilt into a single WMO message.