Dear Richard,
You are absolutely right in that we won't fall out over this intricate subject.
Yet finding the 'real thing' for everyone's perusal, would be useful... i believe.
As an ultimate move, i have e-mailed the Liege Museum Director, with hopes that he sends along an actual listing of Liege proof marks.Expecting it to be supported with a circumstancial text, given to the fact that, as my be seen in this
LINK, some of these marks had a different meaning depending on the dates they were used.
.