A closed explanation can be out of sight without being absent. In a native HTML details disclosure, the visible summary remains available while the additional content is concealed until the disclosure is opened. This is a screen-state distinction, not evidence that the explanation was deleted.
What the closed state tells you
A useful reading note separates the presence of a disclosure label from the explanation it controls. “I cannot see the calculation while the section is closed” is a narrower observation than “the author removed the calculation.” The second statement needs evidence that the first does not provide.
For a native element, the expanded condition is represented by the open state. The browser disclosure model is described in the MDN reference for the details element. A similar-looking custom panel is outside this specific native example.
Worked hypothetical example
Hypothetical example: A page contains the summary “How this example was calculated” and an explanation stating “5/20.” With the disclosure closed, the observation is “summary visible; explanation not visible.” After opening it, the observation is “summary and the 5/20 explanation visible.” The outcome is that the explanation was concealed and then revealed; there is no basis here for saying it was removed, recalculated, or changed.
| State | Visible | Not visible |
|---|---|---|
| Closed | Summary | Explanation, such as 5/20 |
| Open | Summary and explanation | No concealed explanation |
Where the conclusion must stop
If there is no usable action, opening does not reveal content, or the control is not actually a native disclosure or a clearly declared accessible equivalent, leave the cause unconfirmed. Record the summary label and what happened when the control was activated. That gives a reviewer a concrete location to inspect without claiming an unobserved deletion or inventing a cause. Collapsing also does not prove that the total document became smaller or that any server record changed.