Found this description in an article by Nancy Robateille

CLACKAMAS RATTLER, purple standard, named for the County
of Clackamas and for the train that “rattled” through the town.

Joanne

If it still exists, it is as rare as Dupont Supremes. I did a search for it a while ago. There are some posters who claim Cape Code Violetry has it but I haven't asked. It will be interesting to see if you can find it.

Thanks!