You can also use a pose file to force limits, eg: {

version
        {
        number 3.0
        }

actor head
        {
        channels
                {
                targetGeom RoundFace
                        {
                        forceLimits 1
                        }

                }
        }
}

The pose can also set the 'min' and 'max' value of the limits, eg: {

version
        {
        number 3.0
        }
actor head
        {
        channels
                {
                rotateY yrot
                        {
                        forceLimits 1
                        min -35
                        max 35
                        }
                }
        }
}