* Informs the engine that 'len' bytes have been read from the buffer
* (extract operation) or written to the buffer (inject operation).
* The 'len' value MUST NOT be zero. The 'len' value MUST NOT exceed
* Informs the engine that 'len' bytes have been read from the buffer
* (extract operation) or written to the buffer (inject operation).
* The 'len' value MUST NOT be zero. The 'len' value MUST NOT exceed