Notational Conventions

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

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

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

3. Nonterminal symbols are strings of nonspecial italic characters.

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

5. Optional items are enclosed in brackets.

6. Items are grouped together by enclosing them in parentheses.

7. 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