Iframe sandbox
One frame document, four sandbox allow-lists. Each frame reports whether it could run a script, so the effect of the attribute is visible rather than assumed. SAMPLE content only.
Fully locked
sandbox=""Scripts only
sandbox="allow-scripts"Same-origin only
sandbox="allow-same-origin"Scripts and forms
sandbox="allow-scripts allow-forms"The document inside every frame is identical. Only the allow-list differs, so the line each frame shows is a direct read-out of what the attribute permitted.