VITC contains the 64 data bits of the SMPTE linear timecode frame embedded in a new frame structure with extra synchronization bits and an error-detection checksum. The VITC code is always repeated on two adjacent video lines, one in each field. This internal redundancy is exploited by VITC readers, in addition to the standard timecode "flywheel" algorithm.
A video frame may if necessary contain more than one VITC code, recorded on different line-pairs. This is often used in production, where different entities may want to encode different sets of time-code metadata on the same tape.