[ ]

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

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.