Well, it was PoP that reported this hack working on 3.4.2, not I.
He must mean the metadata of the book (I.E: includes what language it is written in).
So check your book before you try to make a working application work for you.
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"No hacks enabled" only because you haven't written any of them yet.

(nor has anybody else, IIRC.)
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If any of the jbpatch stuff seems intimidating, keep in mind that ixtab was working towards his PhD. in Computer Science when he wrote this stuff.