Notational Conventions

This specification uses a modified Backus-Naur Form notation for describing the XDR language. Here is a brief description of the notation:

• The characters |, (, ), [, ], and * are special.

• Terminal symbols are strings of any characters embedded in quotes (").

• Nonterminal symbols are strings of nonspecial italic characters.

• Alternative items are separated by a vertical bar (|).

• Optional items are enclosed in brackets.

• Items are grouped by enclosing them in parentheses.

• A * following an item means 0 or more occurrences of the item.

  For example, consider the following pattern:

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

  An infinite number of strings match this pattern. A few of them are:

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