Abstract: An extensible binary mark-up language is disclosed that is compatible with existing XML standards yet provides significantly improved efficiencies for XML-based data storage and communications, particularly for narrow and low bandwidth communication media. A corresponding extensible non-binary mark-up language is also disclosed that is compatible with the XML standard. This dual-representation common message format (CMF) allows standard XML tools to be utilized in viewing and editing XML-based data and allows a CMF parser to be utilized to convert the XML formatted information into an extensible binary representation for actual communication through a medium or storage on a wide range of media.