Backus-Naur Form Syntax

Each graphic syntax diagram in this reference is followed by a link to a text description of the graphic. The text descriptions consist of a simple variant of Backus-Naur Form (BNF) that includes the following symbols and conventions:

Symbol or Convention Meaning

[ ]

Brackets enclose optional items.

{ }

Braces enclose items only one of which is required.


A vertical bar separates alternatives within brackets or braces.


Ellipsis points show that the preceding syntactic element can be repeated.


Delimiters other than brackets, braces, vertical bars, and ellipses must be entered as shown.


Words appearing in boldface are keywords. They must be typed as shown. (Keywords are case-sensitive in some, but not all, operating systems.) Words that are not in boldface are placeholders for which you must substitute a name or value.