I was just looking through How to Brew, E4 for some explanation and found this: “I should mention that commercial brewers are more likely to use the coarse grind, as-is (CGAI) number from the malt analysis sheet, because that number takes the moisture into account, and helps them more accurately plan their malt usage and maintain better process consistency. On a homebrewing scale, we can be less rigorous and base our efficiency on the more readily available FGDB number. To take moisture into account, multiply the dry basis number by the percentage of dry weight.” This seems to confirm chinaski’s assumption.

I don’t plan to do the math to take moisture into account - staying consistent seems much more important and getting the perfectly accurate number.