Please pardon my naïveté...
I understand that the 992”L” nomenclature indicates “Lever set”, that 992”E” indicates “Elinvar” ... What does the “B” indicate? Is it a design sequence? If so, was there a 992”A”? What differentiated “A” from “B”?
Are there other 992 suffixes?
Thanks

Steve
To answer your questions in order, the "B" represents a significant redesign of the 992 model which came out in 1940 and to quote Hamilton's description "This is a completely new movement from winding arbor to balance wheel, and its parts are not interchangeable with those of previous 992's". However, with the exception of the hairspring, all parts can be interchanged with other 992B's without affecting the function of the watch. Some of the changes included friction fit jewels, an improved Elinvar hairspring, a 2 piece press-fit balance staff, and an improved winding and setting mechanism.
There was not a 992A model. The only other suffix would be the 992P signifying the pendant set version which came out around 1912. The "L" & "P" are not model designations, just configuration descriptors.