G.2 Reading Syntax Diagrams

All syntax diagrams in this book (configuration statements, console commands and utilities) use a com-
mon structure as described in the following table.

Symbol

Description

Êʬ¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬

This symbol indicates the beginning of a
syntax diagram.

¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬ÊÍ

This symbol indicates the end of a syntax
diagram.

¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬Ê

This symbol indicates that the syntax
diagram is continued on the next line.

ʬ¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬

This symbol indicates that the syntax
diagram is a continuation from the pre-
vious line.

¬¬¬¬¬¬¬¬¬¬ required element ¬¬¬¬¬¬¬¬¬¬¬

A required element (keyword or variable)
appears on the main path of the hori-
zontal line. You must specify this ele-
ment.

¬¬¬¬¬§¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬§¬¬¬¬¬

An optional element (keyword or vari-
able) appears below the main path of the
horizontal line. You may or may not
specify this element.

¬¬¬¬¬§¬¬¬¬ required choice 1 ¬¬¬¬§¬¬¬¬¬

choice 2 ¬¬¬¬«

choice

A required choice (keyword or variable)
appears vertically stacked in the main
path of the horizontal line. You must
choose one of the available options.

¬¬¬¬¬§¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬§¬¬¬¬¬

choice 2 ¬¬¬¬«

choice

An optional choice (keyword or variable)
appears vertically stacked below the
main path of the horizontal line. You may
choose one of the available options.

Symbol

Description

¬¬¬¬ ¬¬§¬¬¬¬ option_1 ¬¬¬¬§¬¬¬¬¬¬

option 2 ¬¬¬¬«

option

A keyword with options. Only one of the
available options may be specified. The
underscored option is the default if the
whole keyword statement is not coded.

~¬¬¬¬ default choice 1 ¬¬¬¬¬®

¬¬¬¬¬¦¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¦¬¬¬¬¬

choice 1 ¬¬¬¬«

choice

An optional choice (keyword or variable)
with default appears vertically stacked
with the default value above the main
path of the horizontal line and the remai-
ning optional elements below the main
path of the horizontal line. Only one of
the available options may be specified. If
none of these elements is explicitly
specified, the default above the main line
is taken.

¬¬¬§¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬§¬¬¬

optional choice

¬¬¬§¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬§¬¬¬

,

optional choice

An arrow returning to the left of an ele-
ment below the main path of the hor-
izontal line indicates an optional repeat-
able item. A character within the arrow
path means that repeated items have to
be separated by that character. If there is
no character within the arrow path then
the items are separated by a blank.

~¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬¬®

~¬¬¬¬¬¬¬¬¬¬¬¬ , ¬¬¬¬¬¬¬¬¬¬¬¬®

An arrow returning to the left of an ele-
ment on the main path of the horizontal
line indicates an required repeatable
item. A character within the arrow path
means that repeated items have to be
separated by that character. If there is no
character within the arrow path then the
items are separated by a blank.

¬¬¬¬¬¬¬¬¬¬¬¬

This symbol is a reference to a syntax
segment, which is described separately
below the main syntax diagram. Complex
syntax diagrams are occasionally broken
into separated simpler segments.