Here is my attempt to match the bag letters with model names
Bag "O" = Crown Princess with on-board hose storage
Bag "H" = Princess, Princess II, mini Roto Matic from the 1970's
Bag "M" = Empress
Bag "W" = Whisk hand vac (also will fit the GE version, I guess)
Bag "J" = 1950's Roto-Matic
Bag "B" = Sweet Sixteens (Model Series 1600), and Series 1200 Power Teams, "Ironsides", Quiet Kleen
Bag "C" = Mighty Mite (first version only - not Mighty Mite II or III)
Bag "S" = Empress II "Fast Vacs" (Model Series 1800 and Empress II Power Team (Series 1200), some earlier 1600's
Bag "E/R" = Hand Vac, Whisk, Quick-up
Bag "K" = 1950's and 1960's Super Roto-Matic
Bag "L" = Mobile-Aire, VibraBeat, Parnall Tenten in UK (Model 1000 series)
Bag "V" = 1980's Express Power Teams
The Famous "F & G" Bag! = all "fan-first," "bag-in-the-back" uprights including Dial-A-Naps, Rugulators, Vanguards, ESP's, 1900 Boss, Sanitaire Commercials, and "Automatics" and "Super Automatics" (Model Series 200, 2000, 2300, 1400 and 1900)
Bag "Z" = Ultra Upright
Bag "A" = never knew this existed! As discussed, a narrower version of "F & G" for all soft bag in the back uprights
Bag "P" = Emperor Upright made by Panasonic in Japan
Bag "D" = Series 100 Stick Vacs
BTW, that kewl, groovy 1960's ad for the Eureka Easy Glide on the other post is advertising another Panasonic machine made for Eureka and is basically Eureka's version of General Electric's lightweight electric carpet sweeper. The puny bag is in the base along with the small suction motor. I don't really know why they put a plastic Hoover Concept-like cover on the handle, unless is is just to hide the cord hooks.
Hope this helps the discussion!
Still would love to see proof that a Eureka "Prince" canister vac existed...anyone?
EP Brian