Spoilers for any of the books or any of the episodes of the TV show are not allowed on any channel except the em>ASoIaF channel for the books and the GoT channel for the TV show. Those wishing to discuss spoilers in a room should give advance warning to those present so that anyone who wishes to can leave.
Please keep in mind that since the books have been out a very long time, players who have not read the books or seen the TV show cannot expect to be entirely safe from spoilers. Slip-ups will happen and we do not want to see any major drama resulting from those.
Players who are concerned about spoilers need to be proactive in letting people know if a spoilerish topic comes up on a channel other than Spoilers. However, they should strive to notify others in a friendly fashion.
Also keep in mind that events prior to the start of A Game of Thrones are never considered spoilers and the same goes for thematic details.