This is the insulator I made reference to on ICON back in mid July . This is the logo for Hydro Quebec and I have an example of a CD 122 Dominion 16 ( Not for sale ) that also has this marking. I think the marking has been etched into the glass rather than sandblasted, but it's not an area I'm familier with. Please see pic 2 for a closer look at the marking. Good collecting .......... Robin