.lo? files contain offset data for various purposes, like projectiles and overlays. There are various different file extensions for different purposes:
.loa: Attack Overlays.lob: Zerg Birth Overlays.lod: Landing Dust Overlays.lou: Liftoff Dust Overlays.lof: Building Fire Overlays.loo: Powerup Pickup Offsets.los: Shield/Smoke Overlays.log: Misc..lol: Misc..lox: Misc.
Edited by PyLO