I'm going to answer my own subject question here in order to help others understand the newer SIB file format. (It took me a bit of searching to find out precisely what SIB is.)
- SIB: This is a binary file format for storing external translations. This technology is specifically designed for using with TSILangRT component and allows loading and saving translations at run-time a few times faster than from/to .SIL files.
SIL: External translations that store information in ASCII format.