Bone Roll
In Edit Mode, you can control the bone roll (i.e. the rotation around the Y axis of the bone).
However, after editing the armature, or when using Euler Rotation, you may want to set the bone roll.
Recalculate Roll
Reference
Mode:
Edit Mode
Menu:
Armature ‣ Bone Roll ‣ Recalculate Roll
Shortcut:
Shift-N
Axis Orientation
Local Tangent
Align roll relative to the axis defined by the bone and its parent.
X, Z
Global Axis
Align roll to global X, Y, Z axis.
X, Y, Z
Active Bone
Follow the rotation of the active bone.
View Axis
Set the roll to align with the viewport.
Cursor
Set the roll towards the 3D cursor.
Flip Axis
Reverse the axis direction.
Shortest Rotation
Avoids rolling the bone over 90 degrees from its current value.
Set Roll
Reference
Mode:
Edit Mode
Menu:
Armature ‣ Bone Roll ‣ Set Roll
Shortcut:
Ctrl-R
This is a transform mode where you can edit the roll of all selected bones.