I came across 6 boxs of this film and have been try to get some info on it so I can list it on eBay. I have used tons of tri-x sheet film and roll film over the years. All the information I can find on line is 1954 tri x film started production. but can't find a date on this plate film or the meaning of type B. Most of the photography stuff in the 2 boxes were early 1900. Anyone familiar with it? I would appreciate any information. Thanks