Syntax diagrams

The following example illustrates the syntax for a hypothetical DML DELETE statement. Because the FROM keyword, alias variable, and WHERE clause are optional, they appear below the main command line. In contrast, the tableName variable appears on the command line because the table name is required. If the statement includes a WHERE clause, the clause must contain a search condition or a CURRENT OF clause. (The searchCondition variable appears on the main line for the WHERE clause, indicating that this choice is required.)

The following guidelines provide more information about syntax diagrams:

• Read diagrams from left to right and from top to bottom.
• Required items are on the primary path line.
• Optional items are below the primary path line.
• A recursive (left-pointing) arrow above a stack indicates that you may choose more than one item in the stack.
• An underlined item is a default option.
• If you must select an item from two or more required items, the first item in the stack is shown on the primary path line.
• If you can choose from two or more optional items, they are vertically stacked and the entire stack is below the primary path line.
• Usually, you can select each possible path only once. However, in some cases, a path might be repeated (usually with varying parameters). Statements that allow paths to be repeated are noted in the description of the specific statement, and the repeatable items are flagged with a dagger (†) character.
• Sub-diagrams are indicated by variable names in boldface. When a portion of a syntax diagram cannot fit onto a single page or within the boundary of a column, a variable name represents a sub-diagram that is defined separately from the main diagram.
• If a diagram shows punctuation marks, parentheses, or similar symbols, you must enter them as part of the syntax.
• In general, IBM commands, keywords, clauses, and data types are displayed in uppercase letters. However, if an item can be shortened, the minimum required portion might be shown in uppercase letters, with the remainder in lowercase (for example, CANcel).
• The following conventions apply to variables in syntax diagrams:
  • Variables are typically displayed in lowercase letters and are always italicized.
  • If a variable is represented by two or more words, initial capitals distinguish the second and subsequent words (for example, databaseName).
  • If a variable name occurs more than once, subscripted numbers are used to distinguish one occurrence from another when references would otherwise be ambiguous.
• The use of <DEFLT> indicates that the system-defined default for that value should be used.