We are generally talking NTSC-M on the site, as that is what the final output onto a DVD for North America would be, but I should have been more specific. PAL and NTSC-J both go from IRE0 to IRE 100 on the analogue scale, which kind of equates to 0,0,0 to 235,235,235 on the digital scale, whereas NTSC-M goes from IRE7.5 to IRE100 on the analogue scale, which kind of equates to 16,16,16 to 235,235,235 on the digital scale.
255,255,255 roughly equates to IRE 109 from memory, and is clamped back to IRE100 in most broadcast systems. anything about 235 is considered 'Super White'.
We will be getting into a detailed article on what to do about the IRE7.5 vs IRE 0 situation, and what really happens and where (i.e. inside the various codecs and editing systems) as it is not always what you expect, and you can end up with video stepped up to IRE7.5 more than once resulting in an awful picture.)

Being a PAL man myself, my personal version will defiantely be in PAL, and we will have a whole discussion of the different systems down the track.