Permitted contents #

Permitted attributes #

ⓘ global attributes

Any attributes permitted globally.

ⓘ src = URL potentially surrounded by spaces #

The address of a page that the nested browsing context is to contain.

ⓘ name = browsing-context name #

A valid browsing context name.

Any string, with the following restrictions:

• must not start with a "_" character
• must be at least one character long

ⓘ width = non-negative integer #

The width of the iframe, in CSS pixels.

ⓘ height = non-negative integer #

The height of the iframe, in CSS pixels.

ⓘ sandbox = sandbox “allow” keywords list NEW #

Instructs the UA to “sandbox” the iframe by disallowing/disabling various features, and then (optionally) re-allowing/re-enabling particular features.

The presence of this attribute—even if no value is given (that is, the attribute is specified using empty attribute syntax) or even if the value consists only of space characters—instructs the UA to enforce all the following default sandbox restrictions:

• plugins are disallowed/disabled within the iframe
• forms are disallowed/disabled within the iframe
• scripts are disallowed/disabled within the iframe
• links to other browsing contexts are disallowed/disabled within the iframe
• same-origin treatment of the content hosted by the iframe and the content which hosts the iframe is disallowed/disabled; the iframe is instead treated as being from a unique origin

If any sandbox “allow” keywords are given, they instruct the UA to override particular default sandbox restrictions by re-allowing/re-enabling certain features, as follows:

• allow-forms: re-enables forms
• allow-scripts: re-enables scripts
• allow-top-navigation: re-enables links within the content of the iframe to navigate to its top-level browsing context
• allow-same-origin: re-enables same-origin treatment of the content hosted by the iframe and the content which hosts the iframe (instead of forcing the iframe into a unique origin)

ⓘ seamless = "seamless" or "" (empty string) or empty NEW #

Instructs the UA that the iframe element’s browsing context is to be rendered in a manner that makes it appear to be part of the containing document (seamlessly included in the parent document).

Additional constraints and admonitions #

• The interactive element iframe must not appear as a descendant of the a element.
• The interactive element iframe must not appear as a descendant of the button element.
• The longdesc attribute on the iframe element is obsolete. Use a regular a element to link to the description.
• The align attribute on the iframe element is obsolete. Use CSS instead.
• The allowtransparency attribute on the iframe element is obsolete. Use CSS instead.
• The frameborder attribute on the iframe element is obsolete. Use CSS instead.
• The marginheight attribute on the iframe element is obsolete. Use CSS instead.
• The marginwidth attribute on the iframe element is obsolete. Use CSS instead.
• The scrolling attribute on the iframe element is obsolete. Use CSS instead.

Permitted parent elements #

any element that can contain phrasing elements