Hello,
the start and end flags are 0111 1110:
0111 1110<HDLC Frame>0111 1110
If the same pattern exists within the HDLC frame, a technique called 0-bit insertion is being used, which means after any sequence of 5 consecutive 1's within the payload original data, a 0-bit is inserted. In your case, the entire frame would look like this (inserted 0-bits are marked in bold)
0111 1110<01110011 111010111 011111010 01001101 111110100>0111 1110