The Breidbart Index, developed by Seth Breidbart, is the most significant cancel index in Usenet

Usenet

Usenet is a worldwide distributed Internet discussion system. It developed from the general purpose UUCP architecture of the same name.Duke University graduate students Tom Truscott and Jim Ellis conceived the idea in 1979 and it was established in 1980...

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A cancel index measures the dissemination intensity of substantively identical articles. If the index exceeds a threshold the articles are called newsgroup spam

Newsgroup spam

Newsgroup spam is a type of spam where the targets are Usenet newsgroups.Spamming of Usenet newsgroups actually pre-dates e-mail spam. The first widely recognized Usenet spam was posted on 18 January 1994 by Clarence L. Thomas IV, a sysadmin at Andrews University...

. They can then be removed using third party cancel controls.

Cancel Index

• Crossposting
  Crossposting
  Crossposting is the act of posting the same message to multiple information channels; forums, mailing lists, or newsgroups. Crossposting is perceived as inconsiderate, poor etiquette and is banned from Usenet newsgroups and virtually all email lists...
  
   is the act of posting the same message to multiple newsgroups
• Multiposting is the act of posting the same contents multiple times

The principal idea of the Breidbart-Index is to give these methods different weight.
With a crossposted message less data needs to be transferred and stored.
And excessive crossposts (ECP) are also a likely beginner's error, while excessive multiposts (EMP) suggest deliberate usage of special software.

The crucial issue is categorizing multiple articles as substantively identical.
This includes

• byte-for-byte identical messages
• otherwise identical postings minimally customized for each group it appears in
• advertising the same service
• articles that consist solely of the same signature
• articles which consist of inclusions of other user's postings, but are otherwise identical

Breidbart Index (BI)

The Breidbart Index of a set of articles is defined as the sum of the square root of n, where n is the number of newsgroups to which an article is cross posted

Crossposting

Crossposting is the act of posting the same message to multiple information channels; forums, mailing lists, or newsgroups. Crossposting is perceived as inconsiderate, poor etiquette and is banned from Usenet newsgroups and virtually all email lists...

.

Formula


Example
Two copies of a posting are made, one to 9 groups, and one to 16.

Breidbart-Index, Version 2 (BI2)

A more aggressive criterion, Breidbart Index Version 2, has been proposed. The BI2 is defined as the sum of the square root of n, plus the sum of n, divided by two. A single message would only need to be crossposted to 35 newsgroups to breach the threshold of 20.

Formula


Example
Two copies of a posting are made, one to 9 groups, and one to 16.

Skirvin-Breidbart Index (SBI, BI3)

The name Skirvin-Breidbart Index and the abbreviation SBI are mentionend in the Spam Thresholds FAQ. However, in hierarchy nl.* this index is called BI3.

The SBI is calculated similar to the BI2 but adds up the number of groups in Followup-to: (if present) instead of the number of groups in Newsgroups:. This encourages the use of Followup-to:.

Example
Two posts contain the same text. One is crossposted to 9 groups. The other is crossposted to 16, with four groups in Followup-to:.

BI7 and BI30

In hierarchy de.* the Breidbart index is used with a time range of seven days instead of 45. This is denoted by the abbreviation BI7.

In hierarchy hamster.de.* the Breidbart index is used with a time range of 30 days instead of 45. This is denoted by the abbreviation BI30.

Cancel Index in at.*

This is defined in the FAQ of the group at.usenet.cancel-reports.
The term used in the Call for Votes and in the FAQ is "Cancel-Index".
Unofficial abbreviations are CI und ACI.

The ACI of a single post equals 3 plus the number of groups that the post was sent to. The index of multiple posts is the sum of the indices of the individual posts.

Thresholds

• According to RFC 1036 only the author of the target message or the administrator of the site that injected the message is allowed to send a cancel.
• According to the Spam Thresholds FAQ a BI of 20/45 applies to all hierarchies. Series of articles above this limit may be canceled by everyone.
• In some hierarchies alternative (stricter) limits were defined through a public vote.
• No cancel messages or any derivatives thereof are allowed within free.*.

In fact a cancel message is a just a non-binding request to remove a certain article.
News server

News server

A news server is a set of computer software used to handle Usenet articles. It may also refer to a computer itself which is primarily or solely used for handling Usenet. A reader server provides an interface to read and post articles, generally with the assistance of a news client. A transit...

operators can freely decide on how to implement the conflicting policies.

Hierarchy	Cancel Index	Time Range	Limit	Reports	Definition
*	BI	45	20	news.admin.net-abuse.bulletins
at.*	ACI	45	11	at.usenet.cancel-reports
at.anzeigen.*	ACI	14	4	at.usenet.cancel-reports
bln.*	BI	45	3
de.*	BI	7	5	de.admin.net-abuse.announce
de.alt.dateien.*	BI	45	1	de.admin.net-abuse.announce
de.markt.*	BI	45	2	de.admin.net-abuse.announce
es.*	BI	45	20
fr.*	BI	30	10	fr.usenet.abus.rapports
hamster.de.*	BI	30	3	hamster.cancelreport
it.*	BI	45	20	it.news.net-abuse
muc.*	BI	45	2
nl.*	SBI		10	nl.internet.misbruik.rapport
nrw.*	BI	7	2
schule.*	BI	14	3	schule.cancelreport