FREE: US MNH TD107. U.S Test Stamp. TD107a, Tagged line Coil...TWO ATTACHED shiny gum.

The listing, US MNH TD107. U.S Test Stamp. TD107a, Tagged line Coil...TWO ATTACHED shiny gum. has ended.

US MNH TD107. U.S Test Stamp. TD107a, Tagged line Coil...TWO ATTACHED shiny gum.

I did some research on this unusual set and got an answer about what "tagged" means. I trust this to be correct:
"Tagged means that the Post Office added a phosphorescent substance to a stamp that will glow under a Ultraviolet lamp. This light will cause the stamp to glow. Untaged stamps will not glow under the lamp. It's pretty simple to see, but you need the ultraviolet lamp to see this glow. NOTE: Users of UV light should avoid prolonged exposure , which can burn the eyes. Sunglasses that feature a ullraviolet block or prescription eyeglasses, tinted or plain, screen the rays and provide protection. When I check these type stamps, I do it in darkness. It's alot easier to see the differance" end quote