The module CForeign exports the complete interface of the C-specific portion of the marshalling library. It includes the following modules: CTypes (Section 5.7), CTypesISO (Section 5.8), CString (Section 5.9), and CError (Section 5.5). It will usually be used in conjunction with the language-independent portion of the marshalling library, which is exported by the module Foreign (Section 5.13).
As module CForeign simply re-exports the interface of the other modules listed above, please refer to the documentation of these modules for the details of the provided definitions.