This isn't on the above link.
Trademarks ® exist only when they are used in connection with a good or service.
✖ Pirone v. MacMillan, Inc., 894 F.2d 579, 581 (2d Cir. 1990)
no trade = no trademark.
A mark may lose its trademark protection by failing to police the mark.
When a mark is abandoned, it loses its trademark protection and becomes available for adoption as a new mark by others.
When necessary, however, courts will protect the public from any confusion that may arise from the resumption of use of the mark after it has been abandoned.
✖ Rust Environment & Infrastructure, Inc. v. Teunissen, 131 F.3d 1210 (7th Cir. 1997).