0758ee38_Data_Core__the_Doctor_Who_Wiki__Examples
[Class of story] Trailers [Explanation] Trailers — even the "Next Time" trailer that appears at the end of episodes — are considered spoilers here. They can't be cited before the episode they preview airs. And if they contain information which doesn't make it into the final cut of the episodes, that information is considered a cut scene, and therefore doesn't count. [Rule offended] 1, 3 [Examples] 
A couple of the The Waters of Mars trailers contained information not in the final product. Also, you can't say, "The Tenth Doctor's TARDIS was pulled by reindeer," just because of the 2009 BBC idents
Tardis:Valid sources - Tardis Data Core, the Doctor Who Wiki
Examples