Last modified: 2011-10-17 19:16:55 UTC
With the parameter summary you can prefill the edit summary field. Example: https://en.wikipedia.org/w/index.php?title=Foobar&action=edit&summary=Summary This also works for editing old versions: https://en.wikipedia.org/w/index.php?title=Foobar&action=edit&oldid=454714833&summary=Summary But it doesn't work when you undo a revision: https://en.wikipedia.org/w/index.php?title=Foobar&action=edit&undoafter=454714833&undo=454714890&summary=Summary If the parameter is specified it should even override the default summary for undoing.
Fixed in r100069.