5.1 Notational Conventions

This specification uses an extended Back-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 surrounded by double quotes.
3. Non-terminal symbols are strings of non-special 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 that 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"