The most important concept I learnt about coverage in school was the subsumption hierarchy. For those interested in more details, the Pezze-Young book does the best job of explaining these in chapters 12 & 13. <a href="http://ix.cs.uoregon.edu/~michal/book/" rel="nofollow">http://ix.cs.uoregon.edu/~michal/book/</a><p>I'm surprised that in-practice i've seen only the use of statement & (sometimes) branch coverage being reported. I'd be curious to see if anyone (outside of aviation) has used any other coverage criteria.