E.11.1- Abilities for which you tap the card, and the effects last as long as the card is tapped are called 'tap and hold effects'. [D'Angelo 1998/02/03]
E.11.2- These abilities generate continuous effects that last until the card is untapped. This is similar to a normal time duration effect such as "until end of turn", but is "until the card which generated the effect stops being tapped". [D'Angelo 1995/09/12] See Rule T.8.
E.11.Ruling.1- Although these cards usually only say "as long as
E.11.Ruling.2- If the card which generated the ability untaps before its tap and hold ability actually resolves, the tap and hold effect never takes effect at all. [CompRules 1999/04/23] See Rule T.8.
E.11.Ruling.3- The effect continues even if the card loses its abilities. It only ends if the card untaps or leaves play. [D'Angelo 1995/09/12] This is possible if an artifact is animated by Titania's Song or a land changes type by Phantasmal Terrain.
E.11.Ruling.4- If one of these cards or its target leaves play temporarily by phasing out (see Rule G.27) or otherwise leaving play, the effect will end and will not restart when it re-enters play. [D'Angelo 1996/10/15]