Reading a syntax diagram

About this task

A syntax diagram shows you how to specify a command so that the operating system can correctly interpret what you type.

Read a syntax diagram from left to right and from top to bottom, following the horizontal line (the main path). If the line ends with an arrowhead, the command syntax is continued and the next line starts with an arrowhead. Facing arrowheads mark the end of the command syntax.

When you type a command from the syntax, be sure to include punctuation, such as commas and equal signs.

Parameters are classified as keywords or variables:
  • Keywords represent constants and are shown (in syntax) non italicized. Keywords are case sensitive, for example: -G is a different keyword with different effects than -g.
  • Variables represent names or values you supply and are shown (in syntax) in italics. An example of a variable is filename. You would substitute an actual file name for filename. The values you supply might be case sensitive. A file name of /u/user/foo is a different file name than /u/user/FOO.

The command names, when specified in a UNIX System Services (USS) shell, are case sensitive and must be lowercase. For commands that can be specified in JCL, the command must be in uppercase. For example: // EXEC PGM=ARSLOAD.

A parameter can be a combination of a keyword and a variable.

Required parameters are displayed on the main path.

Read syntax diagramSkip visual syntax diagramCOMMANDrequired parameter

Optional parameters are displayed below the main path.

Read syntax diagramSkip visual syntax diagramCOMMANDoptional parameter

A stack of parameters, with the first parameter displayed on the main path, shows that you must choose one of the parameters.

Read syntax diagramSkip visual syntax diagramCOMMANDrequired choice 1required choice 2

A stack of parameters, with the first parameter displayed below the main path, shows that you can choose one of the parameters.

Read syntax diagramSkip visual syntax diagramCOMMANDoptional choice 1optional choice 2
An arrow returning to the left, above the path, shows that items can be repeated following these conventions:
  • If the repeat arrow contains a break, the item can be repeated in a list with the items separated by blank spaces.
    Read syntax diagramSkip visual syntax diagramCOMMAND repeatable parameter
  • If the repeat arrow contains a comma, the item can be repeated in a list with the items separated by commas.
    Read syntax diagramSkip visual syntax diagramCOMMAND,repeatable parameter
You can repeat items from parameter stacks following the stack conventions for required and optional parameters described previously.

Some syntax diagrams contain parameter stacks within other parameter stacks. You can only repeat items from stacks according to the conventions described previously. That is, if an inner stack does not have a repeat arrow above it but an outer stack does, you can choose only one parameter from the inner stack and combine it with any parameter from the outer stack, and that combination can be repeated. For example, the following diagram shows that you could combine parameter choice2a with parameter choice2 and then you can repeat that combination again (choice2 plus choice2a).

Read syntax diagramSkip visual syntax diagramCOMMAND,parameter choice1parameter choice2parameter choice2aparameter choice2bparameter choice2cparameter choice3

Some commands are preceded by an optional path parameter.

Read syntax diagramSkip visual syntax diagrampathCOMMAND

If you do not supply the path parameter, the system searches the current directory for the command. If the command is not in the current directory, the system continues to search for the command using the directories defined in the PATH environment variable.

Some commands in this section have several formats that accomplish the same task. These commands appear (in syntax) similar to the following:

Read syntax diagramSkip visual syntax diagramCOMMAND FORM1COMMAND FORM2

The description of the command directs you to the correct format to use.