Synchronous Idle (SYN) is the ASCII control character 22 (0x16), represented as ^V in caret notation. Synchronous Idle is used in some synchronous serial communication systems such as Teletype machines or the bisync protocol to provide a signal from which synchronous correction may be achieved between data terminal equipment, particularly when no other character is being transmitted.
The SYN character has the bit pattern 00010110, which has the property that it is distinct from any bit-wise rotation of itself. This helps bit-alignment of sequences of synchronous idles.