Xar (Extensible Archive)
xar (eXtensible ARchive) is an open-source archive format which stores its directory information and other metadata in the form of XML.
The file format starts with a short binary header (which begins with the "magic" sequence consisting of "xar!" expressed as a 32-bit integer made from the ASCII character representations (0x78617221) in network byte order (big-endian). This byte order is used for all multi-byte numbers in the binary portions of the file format.
After the header is the directory information and metadata in XML, using the UTF-8 character encoding.
The remainder of the file consists of the binary data of the archive contents, known as "The Heap".