The "LH" (Left Hand) animation relies heavily on curves.
Autodesk’s native CAT rig is RH-centric. Third-party LH extensions allow you to build bipedal and quadrupedal rigs where the Forward vector points along +X or -X (common in LH game engines) rather than +Y. CG-Animation LH Tools For 3DS Max
This is a game-changer. A button that allows you to change the parent of a hand from "World" to "Chest" to "Prop" dynamically. In vanilla Max, this requires scripting. In LH Tools, it’s a right-click menu. The "LH" (Left Hand) animation relies heavily on curves