<s>
A	O
kill	B-Application
file	I-Application
(	O
also	O
killfile	B-Application
,	O
bozo	B-Application
bin	I-Application
or	O
twit	O
list	O
)	O
is	O
a	O
file	O
used	O
by	O
some	O
Usenet	B-Application
reading	O
programs	O
to	O
discard	O
articles	O
matching	O
some	O
unwanted	O
patterns	O
of	O
subject	O
,	O
author	O
,	O
or	O
other	O
header	O
lines	O
.	O
</s>
<s>
Adding	O
a	O
person	O
or	O
subject	O
to	O
one	O
's	O
kill	B-Application
file	I-Application
means	O
that	O
person	O
or	O
topic	O
will	O
be	O
ignored	O
by	O
one	O
's	O
newsreader	B-Protocol
in	O
the	O
future	O
.	O
</s>
<s>
Kill	B-Application
files	I-Application
were	O
first	O
implemented	O
in	O
Larry	O
Wall	O
's	O
rn	B-Protocol
.	O
</s>
<s>
Sometimes	O
more	O
than	O
one	O
kill	B-Application
file	I-Application
will	O
be	O
used	O
.	O
</s>
<s>
Some	O
newsreader	B-Protocol
programs	O
also	O
allow	O
the	O
user	O
to	O
specify	O
a	O
time	O
period	O
to	O
keep	O
an	O
author	O
in	O
the	O
kill	B-Application
file	I-Application
.	O
</s>
<s>
Web-based	O
forums	O
,	O
including	O
at	O
least	O
some	O
web-based	O
Usenet	B-Application
portals	O
,	O
often	O
have	O
a	O
similar	O
but	O
usually	O
simpler	O
feature	O
called	O
an	O
ignore	O
list	O
,	O
which	O
hides	O
any	O
posts	O
by	O
a	O
specific	O
user	O
,	O
though	O
typically	O
without	O
the	O
ability	O
to	O
ignore	O
posts	O
for	O
reasons	O
other	O
than	O
the	O
username	O
of	O
origin	O
.	O
</s>
<s>
More	O
advanced	O
newsreader	B-Protocol
software	O
like	O
Gnus	B-Operating_System
sometimes	O
provides	O
a	O
more	O
sophisticated	O
form	O
of	O
filter	O
known	O
as	O
scoring	O
,	O
where	O
score	O
files	O
are	O
maintained	O
which	O
use	O
fuzzy	O
logic	O
to	O
apply	O
arbitrarily	O
complex	O
overlapping	O
sets	O
of	O
rules	O
to	O
score	O
articles	O
up	O
or	O
down	O
,	O
with	O
articles	O
being	O
properly	O
killed	O
(	O
ignored	O
by	O
the	O
newsreader	B-Protocol
)	O
only	O
when	O
their	O
weighted	O
score	O
drops	O
below	O
a	O
user-defined	O
threshold	O
.	O
</s>
<s>
Jerry	O
Pournelle	O
wrote	O
in	O
1986	O
of	O
his	O
wish	O
for	O
improvements	O
to	O
an	O
offline	B-Protocol
reader	I-Protocol
for	O
the	O
Byte	O
Information	O
Exchange	O
online	O
service	O
:	O
"	O
What	O
I	O
really	O
need	O
,	O
though	O
,	O
is	O
a	O
program	O
that	O
will	O
...	O
sort	O
through	O
the	O
messages	O
,	O
assigning	O
some	O
to	O
a	O
priority	O
file	O
and	O
others	O
to	O
the	O
bit	O
bucket	O
depending	O
on	O
subject	O
matter	O
and	O
origin	O
"	O
.	O
</s>
<s>
In	O
William	O
Gibson	O
's	O
novel	O
Idoru	O
,	O
the	O
virtual	O
community	O
Hak	O
Nam	O
is	O
built	O
around	O
an	O
"	O
inverted	O
killfile	B-Application
"	O
and	O
is	O
modeled	O
on	O
Kowloon	O
Walled	O
City	O
.	O
</s>
