I would use the STEP I/O library from Open Cascade (or BRL-CAD), they are closer to how we expect someone to read and write STEP models, neither are really tied

I would use the STEP I/O library from Open Cascade (or BRL-CAD), they are closer to how we expect someone to read and write STEP models, neither are really tied to the parent CAD system. The one in BRL-CAD does have problems compiling a feature of the latest STEP standards. One thing missing from the subject of the thread was any history of the exchange formats.