XDR Language Specification

The eXternal Data Representation (XDR) language specification uses an extended Backus Naur form notation for describing the XDR language.

The following is a brief description of the notation:

• The following characters are special characters:

  Item	Description
  |	A vertical bar separates alternative items.
  ( )	Parentheses enclose items that are grouped together.
  [ ]	Brackets enclose optional items.
  ,	A comma separates more than one variable.
  *	An asterisk following an item means 0 or more occurrences of the item.

• Terminal symbols are strings of special and nonspecial characters surrounded by " " (double quotation marks).
• Nonterminal symbols are strings of nonspecial characters.

"a" "very" ("," "very")* ["cold" "and"] "rainy" ("day" | "night")

An infinite number of strings match this pattern, including the following examples:

• "a very rainy day"
• "a very, very rainy day"
• "a very, cold and rainy day"
• "a very, very, very cold and rainy night"