Er... off topic... but, it's copy editing that was required on this, not proof reading. Proof reading is checking the setting of the galley copy (printer's proof copy) for typesetting and transliteration mistakes, misuse of paper volume, etc. Checking the text for appropriate language, spelling, grammar, etc, comes before typesetting or publication, that's copy editing. We typesetters are picky about our jargon.
Retreating back under my typographer's stone... 