The following rules apply to the syntax diagrams used
in this book:
- Arrow
symbols
- Read the syntax diagrams from left to right, from top to bottom,
following the path of the line.
- >>---
- Indicates the beginning of a statement.
- --->
- Indicates that the statement syntax is continued on the next
line.
- >---
- Indicates that a statement is continued from the previous
line.
- ---><
- Indicates the end of a statement.
Diagrams of syntactical units other than complete statements start with the >--- symbol and end with the ---> symbol.
Diagrams of syntactical units other than complete statements
start with the >--- symbol and end with the --->
- Conventions
-
- Keywords, their allowable synonyms, and reserved parameters
appear in uppercase. These items must be entered exactly as shown.
- Variables appear in lowercase italics (for example, column-name).
They represent user-defined parameters or suboptions.
- When entering commands, separate parameters and keywords by
at least one blank if there is no intervening punctuation.
- Enter punctuation marks (slashes, commas, periods, parentheses, quotation
marks, equal signs) and numbers exactly as given.
- Footnotes are shown by a number in parentheses, for example, (1).
- A symbol indicates one blank position.
- Required items
- Required items appear on the horizontal line (the main path).
 >>-REQUIRED_ITEM-----------------------------------------------><
|
- Optional Items
- Optional items appear below the main path.
 >>-REQUIRED_ITEM--+---------------+----------------------------><
'-optional_item-'
|
If an optional item appears above the main path, that item has
no effect on the execution of the statement and is used only for
readability.
 .-optional_item-.
>>-REQUIRED_ITEM--+---------------+----------------------------><
|
- Multiple required or optional items
- If you can choose from two or more items, they appear vertically
in a stack. If you must choose one of the
items, one item of the stack appears on the main path.
 >>-REQUIRED_ITEM--+-required_choice1-+-------------------------><
'-required_choice2-'
|
If choosing one of the items is optional, the entire stack appears
below the main path.
 >>-REQUIRED_ITEM--+------------------+-------------------------><
+-optional_choice1-+
'-optional_choice2-'
|
- Repeatable items
- An arrow returning to the left above the main line indicates
that an item can be repeated.
 .-----------------.
V |
>>-REQUIRED_ITEM----repeatable_item-+--------------------------><
|
If the repeat arrow contains a comma, you must separate repeated
items with a comma.
 .-,---------------.
V |
>>-REQUIRED_ITEM----repeatable_item-+--------------------------><
|
A repeat arrow above a stack indicates that you can specify
more than one of the choices in the stack.
- Default keywords
- Default keywords appear above the main path, and the remaining
choices are shown below the main path.
 .-default_choice--.
>>-REQUIRED_ITEM--+-----------------+--------------------------><
+-optional_choice-+
'-optional_choice-'
|
- Fragments
- Sometimes a diagram must be split into fragments. The fragments
are represented by a letter or fragment name, set off like this: | A |. The fragment follows the end of the main diagram. The
following example shows the use of a fragment.
 >>-STATEMENT--item 1--item 2--| A |----------------------------><
A:
|--+-item 3-+--KEYWORD--+-+--------+-+--------------------------|
'-item 4-' | '-item 5-' |
'-+--------+-'
'-item 6-'
|
|
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