Dale, way back, in the beginning the Wagner pieces were marked just "WAGNER". Then the markings changed to WAGNER SIDNEY O,,,,,,and many other variations.... until WagnerWare Sidney O stylized logos.
So there is a fairly complicated timeline on logos, markings, style, etc.
That is why the Blue Book and Red Book are so important. They show you how complicated this can become, with the many, many, many differences.
(heat ring, no heat ring also)
Griswold is the same thing.... many, many changes over the years.
:)