Displays the link for a diff. The first two numbered parameters are the ID numbers of the revisions (in either order). If only the first parameter is given, the diff is to the previous revision. If only the second is given, the diff is to the current revision. Thus:
Moreover, there's an optional named Boolean parameter,
only, or you can use
diffonly, which, if nonzero, makes the diff URL have diffonly set.
The third, or
text, parameter, yields the text to be displayed: