A hidden interruption is not immediately apparent from the chain's wording. A narrator cites someone whose relationship or era makes direct transmission seem plausible, while investigation reveals that the particular report was not obtained directly.
Its detection requires the transmission formula, the narrator's known habits, documented meetings, parallel chains, and the findings of specialists in hidden defects—not names alone.
Two prominent forms are tadlis and hidden irsal. The first turns on a narrator who is known to have met the cited teacher but may disguise an intermediary; the second involves contemporaries without an established meeting. They are not simply the same technical condition.