Editing Breidbart Index (section)

==Skirvin-Breidbart Index (SBI, BI3)==
The name ''Skirvin-Breidbart Index'' and the abbreviation SBI are mentioned in the ''Spam Thresholds FAQ''.<ref name="thresholds"/> However, in hierarchy nl.* this index is called BI3.<ref name="nl.faq"/>

The SBI is calculated similar to the BI2 but adds up the number of groups in <kbd>Followup-to:</kbd> (if present) instead of the number of groups in <kbd>Newsgroups:</kbd>. 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:.

<math>\frac{\sqrt{9} + \sqrt{16} + 9 + 4}{2} =
\frac{3 + 4 + 9 + 4}{2} = \frac{20}{2} = 10</math>