I for one am prepared to continue beating this dead horse. If we want to wire the tool as per Festool specs, we should get the wiring right. Of course, anyone who cuts off the wrong tab on the pigtail can just reverse it again when wiring the tool so that the hot lead from the pigtail connects where it is supposed to within the tool.
John (CO_JCD) is correct in that the brown lead should be hot and the blue lead common. This holds for the UK and Europe.
The hot/live wire should be the Festool brown connecting to the U.S. black. The neutral/common wire should be the Festool blue connecting to the U.S. white.
Looking at the female end of a standard U.S. Festool Plug-it power cord, holding the connector with the nub pointing up and the valley at the bottom, the left hand hole is the common and the right hand hole is live.
On the plug-it Festool No. 494910 pigtail, the hole with the large "ears" is live and is connected to the brown lead.
To get the pigtail to line up correctly, I had to clip the opposite nub as suggested by Garry (with two Rs). Using Garry's excellent description of nubs, the nub I had to remove is the one between the longer and short "ears". I did NOT cut the nub between the two "ears" that are the same size.
We each will find our own process, but I used a 1/8 inch (3mm) chisel to cut out the nub and then used a 2mm veiner carving chisel to cut the notch wanted by the connector on the Plug-It power cord.
Gary