No need to apologize, the term has been used and disputed for many years and the laughy face meant the comment was very tongue in cheek.. The one most properly used now should be (IMO) simply plate mold.I might say simply a slug if it were just a blank insert but that might open another can of worms.[]
Oh, I was just apologizing in general. The populace these days are easily offended so I take precautions.The way you describe it sounds more logical. The slug plate would be a filler. Like the slugs on an electrical box. Whereas the plate would have the embossing. I will try to remember to call them by the correct terms from now on, but I've been calling them slug plates for 39 years, so I might be slow to change.