Perform some research on the High-level Data Link Control (HDLC) Data-Link protocol and answer the following questions:

1. Framing mechanism. Recall that "frame" is the terminology used to describe a Protocol Data Unit (PDU) at the Data-Link layer.
   1. [What framing technique does HDLC use? (please see the MAC sublayer lecture materials)
   2. Create a simple diagram of the structure of a frame for HDLC that includes the name, size, and position of all fields.
   3. Provide a description of the purpose of each field in the frame.