Do you understand what it means to be a derivative construct as opposed to a primary construct in this context? Please allow me to explain. If (as had been presumed for multiple decades, because no one ever questioned it) every 3.5 mEq's of Ca++ ions liberate 1 mEq of H+ ions, and every 7 mEq's of Mg++ ions liberate 1 mEq of H+ ions, then Residual Alkalinity, a derivative of these two critical, and more importantly critically "fixed" criteria, is factual and has some logical and valid reason to exist, albeit as merely a derivative of these two underlying criteria. The problem, as first brought to our attention by AJ deLange, and then exploded by Barth and Zaman is that the long presumed 3.5 mEq and 7 mEq fixed quantities are in reality wildly moving target variables, and not at all fixed. Looking strictly at Ca++, Baarth and Zaman detailed malts for which the presumed 3.5 mEq spanned under strict lab test conditions from 7 mEq to 21 mEq whereby to liberate 1 mEq of H+. The groundwork supporting Residual Alkalinity was thus utterly destroyed, and right along with it all previous presumptions with regard to how much any given extant quantity of Ca++ ions within the mash water will lower mash pH were also destroyed. No two malts liberate the same quantity of mEq's of H+ ions under the influence of Ca++. And no malts even come close to the long presumed 3.5 mEq's to 1 mEq derivative relationship.