Above, our character has two sets of packs, each of which have their own bones.
The packs on the character's right side are not being affected by any Skeletal Controls while the packs on the character's left are using the Apply a Percentage of Rotation node.
Using this node we give the impression that the packs are moving along with the character's movement.
By changing the Rotation Axis to Refer value we can alter which way the packs rotate, while the Multiplier setting determines how much movement to apply.
Name of target bone to control. This is the main bone chain to modify from.
Name of the source bone to get Transform from.
Rotation Axis To Refer
The axis (X, Y, or Z) to control the Rotation for.
A float value that represents the percentage of the source bone's Rotation to apply to the target bone. When Multiplier is 0, none of the source bone's Rotation is applied to the target bone, and when it is 1.0, all of the source bone's Rotation is applied.
Apply a Percentage of Rotation nodes are also affected by the LOD Threshold system introduced in 4.11. You can find the setting for this in the Details Panel for the Apply a Percentage of Rotation node.