The edge enhancement is applied only to those 1080 lines
that are used in two lines of a 720 frame. For those
lines, the de-aliasing pixels are found and adjusted
so that they belong to only one of the two 720 lines.
The resulting EVR, 720, might overstate the truth some.
That is because enhancement is applied to object edges
but not thin lines or points. On the other hand, when
the 1080 input has reduced resolution, this example
degrades less than other examples. (See the graph
at the bottom of the page.) So on average, the 720
claim is probably reasonable.