Very easy in XML::XSH2, a wrapper around XML::LibXML: 
my $book    := open a.xml ;
my $catalog := open b.xml ;

copy $book/book append $catalog/catalog ;

save :b $catalog ;

[download]
($q=q:Sq=~/;[c](.)(.)/;chr(-||-|5+lengthSq)`"S|oS2"`map{chr |+ord
}map{substrSq`S_+|`|}3E|-|`7**2-3:)=~y+S|`+$1,++print+eval$q,q,a,

[download]

In reply to Re: inserting a tag before a string by choroba
in thread inserting a tag before a string by leoberbert

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