On Tue, 17 Apr 2007 10:35:11 +1000, Alan Peake
wrote:

So how does one prove or disprove the existence of a real reflection
from a virtual discontinuity?

Mac already covered that in the space of four sentences:
On Sun, 15 Apr 2007 18:30:59 -0500, "J. Mc Laughlin" wrote:

One characteristic of a "virtual short" is that its presence or location is
dependent on frequency. Another characteristic is that signals are expected
to exist on both sides of a "virtual short." One characteristic of a
"physical short" is that it does not depend on frequency. Another
characteristic of a "physical short" is that signals exist on only one side
of the "physical short's" location.

73's
Richard Clark, KB7QHC