Quote Originally Posted by Roger Hicks View Post
No, there was a standardized 1/1 pl holder (like 4x5, 5x7/13x18/half plate, 8x10/18x24) -- but alas I no longer have any.
As noted by others, there may have been more common sizes, but not one worldwide standard. With the exception of two Japanese bookform holders, all of my holders are "typical" double-darkslide style and of U.S. origin and every company's is different. Some don't even have ribs for the rib lock, but rather slide into a pocket at end opposite the dark-slide slot. The overall sizes of the film holders vary by almost an inch in the length and width. The plate holders are closer at 3/4".