The number of developers who all have to get HitByBus to lose some important skill or information from the team.

Can be increased by: not having a Guru, CollectiveCodeOwnership, PairProgramming, WritingTheRightThingsDown.

-- KatieLucas

On the teams I have worked on, doing these things is called buying BusInsurance.

BritishCulturalAssumption?  We don't talk about trucks much here, hence also lorry number.

''Offtopic, but what is the derivation of '''lorry'''? --PeteHardie'' Truck. :-)

I had no idea, but according to http://bit.ly/HOBB61 (http://www.dict.org/bin/Dict?Form=Dict2&Database=*&Query=lorry) ,
  [Prob. from lurry to pull or lug.]
The href is verbose and cannot be abbreviated. 8-(

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Is this term any different from the eXtreme Programming term TruckNumber ?
--NissimHadar

I've also heard the term "BusSensitive code". --AristotlePagaltzis

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See TruckNumber, TruckNumberFixed, BusTest