Note 1: A self-synchronizing code permits the proper framing of transmitted code words provided that no uncorrected errors occur in the symbol stream.
Note 2: External synchronization is not required.
Note 3: High-level data link control (HDLC) and Advanced Data Communication Control Procedures (ADCCP) frames represent self-synchronizing code words.
Source: from Federal Standard 1037C and from MIL-STD-188