Many games were available as HD installed as JST first, then were rewritten using whdload (using or not the original JST source for hints)
Then Harry created some macros to help us convert JST slaves to whdload slaves easily (that helped to convert the bulk of JST slaves I had written which didn't exist in whdload format). That helped me to focus on writing whdload slaves instead of wasting my time trying to make JST better than whdload
Then I slowly dropped that macro system to create real whdload source code slaves (much better). Been doing this for almost 20 years now.