+Normally, *sendfile* will serve the file named by the `X-Ash-File`
+header, and fail with a 404 error in case the rest string is not
+empty. However, if the *-f* argument is given, the given 'FILE' will
+always be served instead, and the `X-Ash-File` header and any rest
+string is ignored.
+
+A file's MIME type may be specified explicitly either by using the
+*-c* option, or by passing the header `X-Ash-Content-Type` to
+*sendfile* with the MIME type of the file. That header might, for
+instance, be set using the *set* directives of *dirplex*(1) or
+*patplex*(1).
+