A retcon (from retroactive continuity) is when it is agreed that events that were roleplayed did not actually take place, for some reason or other. On Blood of Dragons, the use of retcons is discouraged and restricted.
The Admin may decide to retcon events that are thematically incorrect, inappropriate and/or unapproved. For example, if a few players come up with a plot to murder Lord Stark (whose player also agrees to the plot) but fail to secure permission from the Admin before going ahead with this plot, then these events would be retconned.
Players may also decide, provided all players involved agree, to retcon private events. If the players involved cannot agree, they may take the matter to the Admin. Players may not decide to retcon any events that have become public knowledge. If a situation arises where one or more players wish to retcon an event that has become public knowledge they must seek the permission of the Admin to do so.