Honestly don't know much about these, but Wound For Life really seems to, and has a cool article about
them today. They focus on Full plate movements which were evidently used often in pocket watches, as
well as thee-quarter plate that bridged the gap between pocket, and wrist watches. Finally they talk about
the Full Bridge movement which are more detailed, technological, high performing, have easy to access to
it's different parts, and much more.
Some pictures for you...
Wound For Life's link with everything...http://www.woundforlife.com/2015/01/09/lessons-wristory-back-plate-evolution/