I'm curious about sewing machine patents.
First, I assume the date we commonly see for a patent is the grant date, and not the application date -- is that right? So I assume the date on a slide plate will be the grant date, and in principle I should be able to search for all patents issued on that date, and somewhere in those results will be the the patent the manufacturer was referring to.
Second, what is the exact significance of a patent being listed on a slide plate? I used to think it was just a list of patents that were "included" in the machine, but does it necessarily include _all_ such patents? Or is it, for example, just patents for which license fees are being paid? (That would imply that patents owned by the manufacturer itself wouldn't be listed.)