A.30.1- The ability is written "Phasing". [D'Angelo 1998/02/03]
A.30.2- A permanent with Phasing ability will "phase out" (see Rule G.27.1) at the beginning of its controller's untap step (see Rule P.5) before untapping any permanents. [CompRules 2001/07/23 - 502.15b]
A.30.3- Phasing is a static ability. See Rule A.3. [CompRules 2001/07/23 - 502.15a]
A.30.4- Phasing is not cumulative. Having more than one instance of this ability has no additional effect. [CompRules 2001/07/23 - 502.15p]
Note- The rules for phasing in and out are described in Rule G.27.