Question about fields in v 1.21

[Fingers]

Those are actually listed in the !hull_files.txt in that folder. Here's the full list.

sysburn - an effect used when a system has been disabled
hullburn - used when the ship has been "killed" and is burning
explode1 - ship explosion effect
explode2 - ship explosion effect with multiple particles
debris - ship parts that go flying when it explodes
fragburn - an effect for burning hull segments after explosion

So by default, sysburn is "sparkjet" and hullburn is "flamejet"