Command definition statements

Command definition allows system users to create additional commands to meet specific application needs.

These commands are similar to the system commands. The defined command calls a program to perform some function. Users can define commands by using command definition statements. The defined command can include the following:

Keyword notation parameters for passing data to programs
Default values for omitted parameters
Parameter validity checking so the program performing the function will have correct input
Prompt text for prompting interactive users

Each command on the system has a Command definition object and a command processing program (CPP).

The CPP is the program called when the command is entered. Because the system performs validity checking when the command is entered, the CPP does not always have to check the parameters passed to it.

The command definition functions can be used to:

Create unique commands needed by system users while keeping a consistent interface for CL command users.
Define alternative versions of CL commands to meet the requirements of system users. This function might include having different defaults for parameter values, or simplifying the commands so that some parameters would not need to be entered. Constant values can be defined for those parameters. The IBM-supplied commands should not be changed.

Table 1. Statements for Defining CL Commands
Statement Type	Statement Name	Related command	Description
Command	CMD	Command Definition (CMD) command	Specifies the prompt text for the command being created. The CMD statement can be anywhere in the source file referred to by the Create Command (CRTCMD) command; one and only one CMD statement must be used in the source file, even if no prompt text is specified for the created command.
Parameter	PARM	Parameter Definition (PARM) command	Defines a parameter of a command being created. A parameter is the means by which a value is passed to the command processing program (CPP). One PARM statement must be used for each parameter that appears in the command being defined.
Element	ELEM	Element Definition (ELEM) command	Used to define the elements of a mixed list (list elements) parameter on a command. A list parameter is a parameter that accepts multiple values that are passed together as consecutive values pointed to by a single keyword.
Qualifier	QUAL	Qualifier Definition (QUAL) command	Describes one part of a qualified name. If a name is the allowed value of a parameter or list element defined in a PARM or ELEM statement, it can be changed to a qualified name by using a QUAL statement for each qualifier used to qualify the name.
Dependency	DEP	Dependent Definition (DEP) command	Defines a required relationship between parameters and parameter values that must be checked. This relationship can refer to either the specific value of a parameter or parameters or to the required presence of parameters.
Prompt Control	PMTCTL	Prompt Control Definition (PMTCTL) command	Specifies a condition that is tested to determine if prompting is done for the parameters whose PARM statement refers to the PMTCTL statement.