Hi Ted - I'm not sure about this, but it seems to me a Rohsohle is an unfinished foundation wall - unfinished in the sense that a sill plate might be added later on, which would increase the height.

Sohle
Fläche, auf der das Haus steht, nennt man Sohle.
oder auch: Bodenfläche von Baugruben, Fundament-, Rohrgräben usw.
http://www.wohnung.net/baulexikon/sohle.html

Sohlplatte foundation slab

http://www.baulexikon.de/dictionary/german/ger_eng_s.htm

Summary: Foundation walls are one of the most important structural elements of your home. They must be strong and supported well before you place vast amounts of heavy soil against them. The backfill soil can quickly crack or push in a concrete wall that is not strong enough to resist the force of the dirt.
http://www.askthebuilder.com/569_Backfilling_a_Foundation_Wa...

Sill Plate
The horizontal wood member that is anchored to the foundation masonry to provide a nailing surface for floors or walls built above.
http://www.hometime.com/Howto/projects/framing/frame_7.htm