B Backus-Naur Form Syntax

Each graphic syntax diagram in this book is followed by a link to a text description of the graphic. The text descriptions are a simple variant of Backus-Naur Form (BNF) syntax that includes the symbols and conventions explained in Table B-1.

Table B-1 Symbols and Conventions for Backus-Naur Form Syntax

Symbol or Convention Meaning
[ ] Brackets enclose one or more optional items.
{ } Braces enclose two or more items, 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 Delimiters other than brackets, braces, vertical bars, and ellipses must be entered as shown.
boldface 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.