The final pile does not identify the restart by itself
Current Law 21 says a ball held up in-goal can lead to a try-line drop-out or five-metre scrum depending on how it entered. Law 12 describes the attacking-team entry leading to a try-line drop-out when the attack fails and the ball legally becomes dead.
Imagine an attacker carrying the ball over the line and being held so it cannot be grounded. Now compare a different entry history involving the defending side taking the ball into its own in-goal. The final view of bodies and an ungrounded ball can look similar while the restart question differs.
Rewind across the line
A camera zooming in after players cross may hide which side supplied that entry. Follow the ball from the last clear possession in the field of play into in-goal before using a remembered held-up shortcut.
This explains why current commentary should retain the ball’s route rather than declaring that every held-up situation has one identical outcome. The illustration does not settle an obscured grounding or preceding foul. It isolates the missing history needed to understand the official’s restart once the ball is determined to be held up.
Questions answered
Is held up alone enough to identify every restart?
No. How the ball entered in-goal matters.
Which earlier frame is useful?
The ball’s movement from the field into in-goal.
Sources & further reading
Official references for the subjects discussed. Service terms and device software can change.