When used in host applications that allow references across multiple projects, Option Private Module prevents a module's contents from being referenced outside its project. In host applications that don't permit such references, for example, standalone versions of Visual Basic, Option Private has no effect.
Option Private Module
If used, the Option Private statement must appear at the module level, before any procedures.
When a module contains Option Private Module, the public parts, for example, variables, objects, and user-defined types declared at the module level, are still available within the project containing the module, but they are not available to other applications or projects.
Option Private is only useful for host applications that support simultaneous loading of multiple projects and permit references between the loaded projects. For example, Microsoft Excel permits loading of multiple projects, and Option Private Module can be used to restrict cross-project visibility. Although Visual Basic permits loading of multiple projects, references between projects are never permitted in Visual Basic.
This example demonstrates the Option Private statement, which is used at module level to indicate that the entire module is private. With Option Private Module, module-level parts not declared Private are available to other modules in the project, but not to other projects or applications.
Option Private Module ' Indicates that module is private.