I have a character with a "head" and a "tail". I attach them together with a pivot joint, but I only want the tail to rotate a maximum of 5 degrees in either direction:

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myJoint = physics.newJoint( "pivot", head, tail, head.x, head.y )
myJoint.isLimitEnabled = true
myJoint:setRotationLimits( -5, 5 )