This article is from the ER FAQ, by Rose Cooper email@example.com with numerous contributions by others.
With so many TV shows featuring cliffhanger-type plots this spring,
this has become a hot topic in a lot of Usenet groups. Basically, a
spoiler is any piece of information about an upcoming episode. It got that
name because for those people who like to go into each episode knowing
absolutely nothing but what happened in previous episodes, being told
certain bits of information can "spoil" their enjoyment of that episode.
Spoiler information can range from things as major as the fact that a
character is going to die to something as relatively mundane as the fact
that a certain seldom-seen character is going to make a surprise
reappearance. Because some people don't mind knowing stuff in advance,
it's okay to include spoilers in your posts, but there are a few basic
guidelines to follow to avoid ticking people off:
1) Always insert the word "Spoiler" in your subject header,
especially if you're following up to a thread that didn't
originally have spoilers in it;
2) NEVER put an actual spoiler ("I can't believe Carter is going
to get hit by a train!", for instance) in your subject header.
(And that is an imaginary example, by the way.) Even if you
were to leave Carter's name out in that particular example,
the mere knowledge that *any* of the characters is going to get
hit by a train constitutes a spoiler for most people. A good
example of a spoiler-safe header is something like "What I heard
about the season premiere - Spoiler.";
3) Try very hard to include a lot of blank lines in a post before
the spoiler information, so that some unfortunate soul whose
newsreader won't allow him/her to scan subject headers, won't
unwittingly stumble across a spoiler.
So, you may be asking, do I have to keep doing this for every episode
in perpetuity? No. The generally accepted Usenet rule is that once an
episode airs, spoilers don't apply to it.
(Thanks to Alan Sepinwall <firstname.lastname@example.org> for
supplying the above text.)
4) In addition to the SPOILER category, Common Practice by the
a.t.e. Old Hats says to please put some type of notation,
category-wise, in your subject headers for the following types
First suggested here by P.A. Behrer, the [TNT] category denotes
discussion of episodes being shown on US TNT (syndicated cable),
all of which will be reruns for a great majority of a.t.e'ers.
While not strictly spoilers, discussions of long-past episodes
tend to go over well-trod ground, which if not noted by the [TNT]
category, might cause the more anal or easily aggravated amongst
me...uh, us...to grit teeth at Yet Another mentioning of the factoid
that, Hey, Doug Has A Son, Kewl!
[OT] (or [TAN]):
Sooner or later, almost every long thread (related group of
posts, generally under the same subject header) will "suffer" from
topic-drift. It's almost inevitable, and is often quite enjoyable.
But if one knows one is *starting* a wholly-unrelated-to-ER post
(i.e., "Why Rotties Are So Kewl!"), it is considered Good Manners
to warn those of us who don't care to read wholly-unrelated-to-ER
posts by including [OT] (Off-Topic) or [TAN] [Tangent] warnings in
your subject line. Those who revel in OT posts are then free to
revel at will, which should be done unharassed by those who don't.
The usually snarky alt.tv.homicide currently has an excellent sample
of OT-marked threads (though it is expected that once the off-season
comes to a close, so will the majority of OT threads).