The application developer may need to run similar applications in different languages. He has to know whether this is possible within the technology he is acquiring. He also has to check what kind of adaptation is needed when moving from one language to another. For example if the voice system uses a speech recognition module then he has to know if moving from one language to another requires downloading of the appropriate references or if he has to configure and tune various other parameters (thresholds, gains, ...) depending on the second language.