The OpenMW project is made up of three distinct subsystems:
We have a strict Policy about dependencies between these subsystems.
World Model 
Up to version 1.0 we will use the original esm/esp formats nearly unchanged. Currently OpenMW ignores any pre-compiled scripts and does JIT-compiling instead. The new CS will not generate pre-compiled scripts either.
A documentation of the original format can be found here:
Please note, that this documentation is not fully complete and in some cases not fully correct either.