Constructing Commands

Command statements consist of commands and qualifying parameters.

Verbs

Specify the operation to perform.

For example, RETURN, COMPUTE, IF, DISPLAY, OBTAIN, and WRITE PRINTER are commands.

Parameters

Qualify commands and specify additional operations to perform. Parameters can be:

Keywords, which are system-defined values. Each keyword must be specified as shown in the documentation. (The required portion of each keyword is shown in capital letters.)
For example, in the RETURN CLEAR statement, CLEAR is a keyword that qualifies the operation of RETURN.
Variable terms, which show where user-defined values can be coded in process command syntax.
For example, in the following command statement, dialog-name is a variable term:
```
RETURN TO dialog-name
```
Syntax and examples of variable terms are presented in the remaining chapters of this volume. The following table summarizes the types of variable terms that can be used.

Type of variable	Purpose
Arithmetic expression	Specifies a simple or compound arithmetic operation
Built-in function	Specifies evaluation of a value according to a predefined operation
Conditional expression	Specifies test conditions
Constant	Specifies a value to be used in command processing
Error expression	Permits the return of error status codes to a dialog
Variable data field	Supplies the name of a user- or system-supplied data field for use in command processing