-*dirplex* will send a built-in 404 response by default, but any
-`.htrc` file or global configuration may define a request handler
-named `.notfound` to customize the behavior. Note that, unlike
-successful requests, such a handler will not be passed the
-`X-Ash-File` header.
+By default, *dirplex* will send a built-in 404 response, but there are
+two ways to customize the response:
+
+First, *match* stanzas with the type *notfound* will be matched
+against any request that would result in a 404 error. The filename for
+such matching is that of the last succesfully found component, which
+may be a directory, for example in case a name component could not be
+found in the real filesystem; or a file, for example in case a file
+was found, but not matched by any *match* stanzas.
+
+Otherwise, any request that would result in a 404 response but is
+matched by no *notfound* stanza is instead passed to a default handler
+named `.notfound`, which is handled internally in *dirplex* by
+default, but may be overridden just as any other handler may be in a
+`.htrc` file or by global configuration. Note, however, that any
+request not matched by a *notfound* stanza will not have the
+`X-Ash-File` header added to it.