How to Interpret Syntax Diagrams

The syntax diagrams in this book use the following conventions:

>>-PARAMETER--(--+------------------+--user-defined-value--)---><
                 '-PREDEFINED-VALUE-'
 

Read the syntax diagram from left to right, and from top to bottom, following the path of the line.

The >>-- symbol indicates the beginning of the syntax diagram.

The -->< symbol indicates the end of the syntax diagram.

The ---> symbol indicates that the statement syntax is continued on the next line.

The >--- symbol indicates that a statement is continued from the previous line.

The --(--)-- symbol indicates that the parameter or value must be entered in parentheses.

Required parameters appear on the base line and must be entered. Optional parameters appear below the base line and do not need to be entered. In the following sample, you must enter REQUIRED-PARAMETER and a value for it, but you do not need to enter OPTIONAL-PARAMETER or a value for it.

>>-REQUIRED-PARAMETER--(--+-PREDEFINED-VALUE---+--)------------->
                          '-user-defined-value-'
 
>--+--------------------------------------------------+--------><
   '-OPTIONAL-PARAMETER--(--+-PREDEFINED-VALUE---+--)-'
                            '-user-defined-value-'
 

Default values appear above the base line and do not need to be entered. They are used when you do not specify a parameter. In the following sample, you can enter DEFAULT-VALUE, OTHER-PREDEFINED-VALUE, or nothing. If you enter nothing, DEFAULT-VALUE is assumed.

                 .-DEFAULT-VALUE----------.
>>-PARAMETER--(--+-OTHER-PREDEFINED-VALUE-+--)-----------------><
 

Optional values are indicated by a blank line. The blank line indicates that a value from the first group (OPTIONAL-VALUE1, OPTIONAL-VALUE2, user-defined-value) does not need to be entered. For example, based on the syntax below, you could enter KEYWORD(REQUIRED-VALUE).

                 .-OPTIONAL-VALUE1----.
>>-PARAMETER--(--+--------------------+----REQUIRED-VALUE----)-><
                 +-OPTIONAL-VALUE2----+
                 '-user-defined-value-'
 

Repeated values can be specified for some parameters. The comma (,) in the following sample indicates that each user-defined-value must be separated by a comma.

               .-,----------------------.
               V                        |
>>-KEYWORD--(------user-defined-value---+--)-------------------><