Currently we can call "pos" and "pos_local"(allegedly) on a bone, and it will move it on IK.
Perhaps pos can be renamed ik and ik_local, because it is confusing as I thought it actually moved the bone's offset, rather than perform IK on the bone to get it near the given values.
If not, offset and offset_local will work for this.
Offsetting the bone would work exactly as the animation format's position format does.
Offsetting bone is important, especially for AR, where the whole body may move. Without having a the ability to move bones, we cannot move the pelvis bone, which results in the avatar looking like they are gravitating around a central point, rather than resulting in realistic movement.