You use commands when writing procedure and test code in the Program, System, and Driver modules. How a module accesses commands depends on where you created the command and whether you selected the Public property of the command. A module can access its own commands and the public commands defined in the modules below or next to it, as shown in the following illustration:
Specifically, each module accesses commands as follows:
A Program can access commands defined within it as well as public commands defined in the System and Drivers. If the command you want to create is used only in your program, define it as a Program command.
A System can access commands defined within it as well as public commands defined in its drivers. If the command you want to create uses several drivers and is used by several programs or by the system, define it as a System command.
A Driver can access commands defined within it as well as commands of other drivers. If the command you want to create applies only to an individual driver, define it as a Driver command.
For information on making a command public, see Setting Command Properties.