# File Mappers

File mappers can be used, for example, when files are being copied, moved, archived, or unarchived. The purpose of a file mapper is to select the target files name and destination.

Examples:

- The IdentityMapper is a trivial file mapper, which leaves all file names are unchanged. This is mainly useful as a default file mapper.
- The FileNameExtensionMapper changes the file names extension. This can be used, for example, when you run the FOP transformer to produce PDF. Of course, you would want the created files to have the extension `.pdf`, rather than `.xml`.