I am reading The Crying of Lot 49, wherein a fictional organization called "Trystero", that may or may not exist in the story, is associated with a symbol called the "muted post horn". The author, Thomas Pynchon, invented this organization and its symbol in this story, amongst other things.
The symbol as depicted on book covers became popular, and can be found as graffiti, and markings on signs, etc. since the 1960s, when the book was published.
I've noticed that several online vendors are selling items with the Trystero symbol, and I wonder if any legal rights issues come into play.
For instance, a print-on-demand service, CafePress, sells coffee mugs, water bottles, bags, shirts, etc, emblazoned with the symbol, or a facsimile thereof, and are advertised as 'Trystero' products. The designs aren't created by CafePress themselves, but rather are created by users of the site, who get some portion of the sales of the items.
There is also a coffee roaster that has named itself Trystero Coffee, and has the symbol on its products.
The above products and business openly acknowledge use of the name and symbol as an homage to the novel.
I'm vaguely aware of copyright owners forbidding money-making reproductions of their creative work-- mostly characters, such as non-Disney Mickey Mouse cartoons, or Calvin and Hobbes dolls and stickers.
Could Trystero the organization and its symbol be afforded such protection? Are these vendors simply not being persued?