Doug and Mark,
I had been aware of that very good article you referenced Doug, and on reviewing it just now thought to have a second look at M0 versus M1 using an i1Pro2 with i1Profiler and Epson Glossy Photo Paper which is resplendent with FWAs. Please see the attached two screen grabs. First X-Rite's description of these conditions on the GUI itself. As usual for X-Rite, inadequate. They tell us that M1 is D50 but fail to tell us that UV is included, whereas they say this for M0. Those who don't know could be confused into thinking that M1 doesn't include it because it's not mentioned. Anyhow, moving beyond that, the other thing they don't tell you is that it doesn't matter which of those measurement conditions you select when measuring a patch in Measure Chart mode, because the spectro and software return all three measurements at once and they are identical (i.e. the differences between M0, M1 and M2 are the same) regardless of which data parameter we select for making the measurement. This can also confuse people who don't know. Of course none of this confusion would need to occur were it not for the lack of a manual accompanying this kit. To date, as far as I know, neither X-Rite nor any third party have written a manual. Shame.
Turning to the results, as to be expected, John Seymour is correct that M0 and M1 have different sensitivity to FWA presence in the paper. This is evident from the bluer outcome in the b* channel comparing M1 with M0. Not to say, however, that M0 is insensitive to FWAs - it still shows up as -8.03, versus -10.72 for M1, while the M2 UV cut measurement indicates the paper is actually yellowish at b*1.92. You'd never know it looking at the stuff!
Anyhow, I agree with Mark HMG this is OT, but thought it useful just to round-off the discussion looking at this evidence, arising from thoughts rereading the Seymour piece.