Here is the official Spoiler Policy of the Medaka Box Wiki, and the meaning of this page is to list what to do and NOT to do with spoiler and fanscanned information.
What Is A Spoiler?
We suggest you take a look at this article before you read the following content, so you will understand what we are talking about.
Here are the first lines of the article:
Spoiler is Genex slang for any element of any summary or description of any piece of fiction that reveals any plot element which will give away the outcome of a dramatic episode within the work of fiction, or the conclusion of the entire work. Because enjoyment of fiction sometimes depends upon the dramatic tension and suspense which arising within it, the external revelation of such plot elements can "spoil" the enjoyment that some consumers of the narrative would otherwise have experienced.
Manga Spoilers and Non-Fanscanned Content
We actually consider that until the chapter is released by a publicly accessible site, that chapter's information is considered to be a spoiler. Until the proper ENGLISH fanscan is released, it is simply FORBIDDEN to add any information from it (including the chapter's title), and the edits should be reverted on sight. The person who adds spoiling information will be warned about it only once. The information, as insignificant it might seem, might ruin the fun of reading a just-released chapter for some.
To be clearer: If you can read only scripts and can't see the true chapter, don't add the information on the wiki. That's against our policy: No spoilers.
We have a dedicated Spoiler page on the wiki. You are allowed to put spoilers on that page, but not on any others.
Manga Spoilers and Fanscanned Content
As soon as the ENGLISH chapter is online, you are allowed to add information. An ENGLISH chapter being online means that you CAN read it, with the images, not just a little script. After the release, you are totally free to add the SURE information on the pages of the wiki; we consider that this is clear that the wiki gives information about the latest releases and that the person who will read that article KNOWS that there will be content he might not know.
To be clearer: If you can read the online "scan" of the ENGLISH chapter, then, you can add information from it; that's allowed by our policy.
It is forbidden to add information from an episode of the anime to the wiki if it is not yet available in English. We allow an episode to be added only when an English subtitled version of it is available to watch on a publicly accessible site. In addition, the titles of the upcoming episode may not be added to the wiki until the above conditions are met, as the titles often give away details of a plot point, or the involvement of certain characters. This is also considered to be a spoiler. In short, if the episode is not available in English, no details about it may be added.
If a Chapter/Episode is Only Just Released
If you are adding information from an episode or chapter that has only just been released in English (or if it is likely that other users are unaware of its release), use the edit summary box to state that the chapter/episode is indeed out and state the site where you read it (an exact link would be appreciated). This will allow others to verify that the chapter/episode is out and that the information you are adding is correct. It will also reduce the likelihood of your edit being reverted and you getting into trouble with an Admin for violating this policy. And it is a good service to let the rest of the community know that it has been released.
New Fanscan and Fansub Groups
From time to time, a new fanscan group arrives on the scene. In their early days, any such group is likely to be little known and may not be widely available. If they happen to be the first group to release a new chapter/episode in English, it is very important that you state as much in the edit summary box, and/or let an Admin know to avoid any issues. It is especially important if they do not allow their material to be published on a widely known and accessible site. We cannot be expected to find them if we are unaware of their existence.
Failure To Comply
The first thing that will happen will simply be a revert of the spoiler edits with a reason indicating that spoilers should be avoided.
The users will usually be warned, and such warning might it be by a message on the individual's talk page or by a clear revert message.
If the spoiler-adding repeats itself, the page will probably be protected until the chapter's out.
If you don't read or respect the policy, do it at your own risk, and you will most likely be blocked if you don't stop after the first or the second revert. YOU are able to read if you are on a wiki, so you see the "Don't add spoiler" advert, and the reverted edits, yet you still choose to add spoilers? Fine, we choose to block you.