Use
You can create, display, change, delete, rename, and copy external commands. SAP commands cannot, however, be changed in customer systems.
External commands can only be processed individually. For example, you cannot delete several external commands at the same time. External commands can only be processed by one user at a time.
Procedure
To maintain external commands:
From the main R/3 menu, choose Tools ® CCMS, Configuration ® External Commands.
Alternatively, call Transaction SM69.
You can then display or change the external commands. To display a list of all external commands defined in the system, choose Display « Change.
External commands are uniquely identified by a user-definable logical name and an operating system.
You can specify the name of an R/3 function module which, when executed, decides whether the specific command should be executed or not. The interface to this check module must be the same as for the check module ' SXPG_DUMMY_COMMAND_CHECK ' delivered by SAP.

SAP recommends that you copy ' SXPG_DUMMY_COMMAND_CHECK ' before using it. Do not change this function module in your system.

Command names beginning with ‘X’ or ‘Z’ are reserved for customer commands.

Before Release 3.0C, external commands must be confirmed in the target system after a transport (between customer systems). Otherwise they are considered invalid. When you call the list of external commands, the system informs you of the need to confirm the commands.
See also:
What Information is Displayed? Additional Parameters Executing External Commands