|------- SCHC Fragment Header -------|
         |-- T --|-M-|-- N --|-- U --|
+-- ... -+- ... -+---+- ... -+- ... -+-----...-----+~~~~~~~~~~~~~~~~~
| RuleID | DTag  | W | 11..1 |  RCS  | FragPayload | pad. (as needed)
+-- ... -+- ... -+---+- ... -+- ... -+-----...-----+~~~~~~~~~~~~~~~~~
                       (FCN)