nsIDocShell
long keeps track of the previous shtransaction index and the current shtransaction index at the time that the doc shell begins to load.
...nsaction index and the current shtransaction index at the time that the doc shell begins to load.

HTMLIFrameElement - Web APIs
mbedded document must agree to enforce upon itself.
... specifications specification status comment html living standardthe definition of 'htmliframeelement' in that specification.

HTMLImageElement.vspace - Web APIs
the obsolete vspace property of the htmlimageelement interface specifies the number of pixels of empty space to leave empty on the top and bottom of the <img> element when laying out the page.
... the obsolete vspace property of the htmlimageelement interface specifies the number of pixels of empty space to leave empty on the top and bottom of the <img> element when laying out the page.

Style System Overview - Archive of obsolete content
ome), and require large numbers of allocations to construct.

Mozilla Quirks Mode Behavior
ter).

<frame> - HTML: Hypertext Markup Language
e.

<iframe>: The Inline Frame element - HTML: Hypertext Markup Language
of this element with respect to the surrounding context.