Perhaps a more realistic example. Simply strip the markup in richTitle and you'd be left with "The story of 1: an imaginary tale." <titleInfo> <nonSort>The </nonSort> <title>story of √(−1)</title> <subTitle>an imaginary tale</subTitle> <titleInfo> <extension xmlns:m="http://www.w3.org/1998/Math/MathML"> <richTitle xmlns="http:whatever>The story of <m:math> <m:apply> <m:root/> <m:apply> <m:minus/> <m:cn>1</m:cn> </m:apply> </m:apply> </m:math>: an imaginary tale</richTitle> </extension>