The AddType directive adds entries to the server default typing information and generates a particular extension type. This directive overrides any conflicting entries in the TypesConfig file.
AddType type/subtype extension
type/subtype is the MIME-like type for the document.
extension is the filename extension to map to this type.
You can use several AddType directives in the configuration file.
srm.cfg
The default types are located in the types configuration files.
AddType text/plain doc
AddType text/plain txt