http://www.rfc-editor.org/rfc/rfc1014.txt
RFC 1014: XDR: External Data Representation standard, 1987-06-01T23:00:00-00:00XDR is a standard for the description and encoding of data. It is useful for transferring data between different computer architectures. XDR fits into ISO presentation layer, and is roughly analogous in purpose to X.409, ISO Abstract Syntax Notation. The major difference between these two is that XDR uses implicit typing, while X.409 uses explicit typing. This RFC is distributed for information only, it does not establish a Internet standard.