Dicretion can be used on level variations but if you start to use it alot then the CAA get very jumpy and can remove the variation. if you have a variation and say every week you use discretion then either a new variation needs to be applied for or the CAA will pull the variation. Contact the CAA the do not mind and you do not have to give your name or company. they are very helpful i have used them many times to claify things. as the drivers always like to put one on you.