EntryPoint Property
Specifies an entry point within a .dll custom action. Applies only to unmanaged or native .dll custom actions.
Remarks
The Entrypoint property is the exported function name in an unmanaged DLL.
The Custom Actions editor provides default values of Install, Commit, Rollback, or Uninstall, depending on which sequence the action is inserted beneath. You must assure that your .dll file exports a function with the same name, or else change this property to match a function export defined in your .dll file.
Note
This property is ignored when the InstallerClass property is set to true.