+=item C<post_data>
+
+If the client sends data in the request body with the content type of
+either C<application/json> or C<multipart/form-data>, the content will
+be stored in the global request object, too. It can be retrieved via
+the C<post_data> function.
+
+For content type C<multipart/form-data> the same data is additionally
+stored in the global C<$::form> instance, potentially overwriting
+parameters given in the URL. This is done primarily for compatibility
+purposes with existing code that expects all parameters to be present
+in C<$::form>.
+
+For content type C<application/json> the data is only available in
+C<$::request>. The reason is that the top-level data in a JSON
+documents doesn't have to be an object which could be mapped to the
+hash C<$::form>. Instead, the top-level data can also be an
+array. Additionally keeping the namespaces of URL and POST parameters
+separate is cleaner and allows for fewer accidental conflicts.
+