A cancel index measures the dissemination intensity of substantively identical articles.
If the index exceeds a threshold the articles are called newsgroup spam.
The principal idea of the Breidbart-Index is to give these methods different weight.
[1] 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.
[2] This includes 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.
A more aggressive criterion, Breidbart Index Version 2, has been proposed.
[2] A single message would only need to be crossposted to 35 newsgroups to breach the threshold of 20.
The name Skirvin-Breidbart Index and the abbreviation SBI are mentioned in the Spam Thresholds FAQ.
[3] 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:.
* the Breidbart index is used with a time range of seven days instead of 45.
* the Breidbart index is used with a time range of 30 days instead of 45.
The term used in the Call for Votes [7] and in the FAQ is "Cancel-Index".
In fact a cancel message is a just a non-binding request to remove a certain article.
News server operators can freely decide on how to implement the conflicting policies.