This part of ISO/IEC 23001 specifies BSDL (Bitstream Syntax Description Language), a language based on W3C XML Schema to describe the structure of a bitstream with an XML document named BS Description.BSDL provides a normative grammar to describe in XML the high-level syntax of a bitstream; the resulting XML document is called a Bitstream Syntax Description (BS Description, BSD). This description is not meant to replace the original binary format, but acts as an additional layer, similar to metadata. In most cases, it will not describe the bitstream on a bit-per-bit basis, but rather address its high-level structure, e.g., how the bitstream is organized in