Sorry sir/ma'am, a bit late to the party. https://www.elitetrader.com/et/thre...increase-in-margin.307804/page-3#post-4427248
BTW, with regards to that Cotton NZ14 spread they referred to later in the article, the last minute liquidation before FND did seriously disrupt the market (although not really a market non-commercials would be in at that point):
Gary DeWaal, the article author, has apparently NEVER seen a Cotton Futures order book. It's worse than Unleaded Gasoline ! Cotton is, IMHO, the gappiest thinnest order book I know of - and that includes the metals.