Calculating a zero-coupon bond's CAV becomes important if the bond carries a call provision. This is because call provisions for zero-coupon bonds are typically linked to the bond's CAV. The provision will usually stipulate that the issuer can call the bond on a specific date at a price that is a premium to the bond's CAV.
A zero-coupon bond is trading at a premium if it costs more than its CAV at that specific point in time. Conversely, the zero-coupon bond is trading at a discount if it costs less than its CAV.
Investment dictionary. Academic. 2012.