It would be very beneficial to have the ability to limit spring settings on specific local axis'.
Application that most everyone has run into is running and driving with female avatars. You need the realism of spring hair and breasts, particularly in a moving vehicle, without the hair hanging out the back hatch and the breasts poking through her back.
Local axis limitations in spring settings could save tons of time and space by reducing multiple scenes, projects, and reduced setting controls. Limit the spring settings for the breasts in the -X direction to prevent breasts through the back and hair in the +X direction to prevent hair breaking through the avatars back.
Several potential applications of this tool could be extremely valuable.