More than one master program; select by naming convention

What causes this issue?

More than one main program was found for the current include during
navigation.
The system has chosen the most appropriate main program based on the
naming conventions.
In exceptional cases, this may be the wrong navigation target.

System Response

The system issues an error message and will not allow you to continue with this transaction until the error is resolved.

How to fix this error?

To choose another program as the main program, set the main program
before navigation by choosing Utilities --> Main programs.

Procedure for System Administrators

Error message extract from SAP system. Copyright SAP SE.