Continuation Links
Paths that are too long for one line use continuation links. Continuation links are circled letters indicating the beginning and end of a link:
When you see a circled letter in a syntax diagram, go to the corresponding circled letter and continue reading.
Required entries appear on the main path:
If you can choose from more than one entry, the choices appear vertically, in a stack. The first entry appears on the main path:
You may choose to include or disregard optional entries. Optional entries appear below the main path:
If you can optionally choose from more than one entry, all the choices appear below the main path:
Some commands and statements treat one of the optional choices as a default value. This value is UNDERLINED. It is presumed to be selected if you type the command or statement without specifying one of the options.
String literals appear in apostrophes:
If a keyword or a reserved word has a valid abbreviation, the unabbreviated form always appears on the main path. The shortest valid abbreviation appears beneath.
In the above syntax, the following formats are valid:
A loop is an entry or a group of entries that you can repeat one or more times. Syntax diagrams show loops as a return path above the main path, over the item or items that you can repeat:
Read loops from right to left.
The following conventions apply to loops:
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IF... |
THEN... |
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there is a maximum number of entries allowed |
the number appears in a circle on the return path. In the example, you may type cname a maximum of 4 times. |
|
there is a minimum number of entries required |
the number appears in a square on the return path. In the example, you must type at least three groups of column names. |
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a separator character is required between entries |
the character appears on the return path. If the diagram does not show a separator character, use one blank space. In the example, the separator character is a comma. |
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a delimiter character is required around entries |
the beginning and end characters appear outside the return path. Generally, a space is not needed between delimiter characters and entries. In the example, the delimiter characters are the left and right parentheses. |
Sometimes a piece of a syntax phrase is too large to fit into the diagram. Such a phrase is indicated by a break in the path, marked by (|) terminators on each side of the break. The name for the excerpted piece appears between the terminators in boldface type.
The boldface excerpt name and the excerpted phrase appears immediately after the main diagram. The excerpted phrase starts and ends with a plain horizontal line:
In a syntax diagram, it is possible for any number of phrases to be legitimate:
In this example, any of the following phrases are legitimate:
The alphanumeric string that appears in the lower right corner of every diagram is an internal identifier used to catalog the diagram. The text never refers to this string.