In the Material Room for the Image Node there are dials for U offset and V offset. I'm wondering if this means that Poser can use models with UV maps that are outside the typical 0-1 range.
If so, if for example a group of UV islands were in the 0 to -1 (that's zero to negative 1) range, then I assume the U offset would be -1? For an object that had UVs for certain materials  in that range, that is. And so on for the U offset and into the other possible ranges.

I don't really have time to test it out, just wondering if anyone knows offhand. It could make a difference for as far as some things I want to do with Poser.

If you need to flip or mirror a section, you can just set the U scale (mirror)
or the V scale (flip) to -1.  This is often helpful in a situation where a planar
map happens to be facing the wrong way.... it's a lot easier than finding the
section on the actual JPG and flipping it in Photoshop.

The offsets would help in the case where e.g. the V dimension starts from -1
and goes to 0 in the forward direction.  You could set the V offset to +1 and
it would pull this section up into the proper range.  One caveat: the offsets
will "wrap" the mapping if you're not careful.  If the map for this section exactly
matches the scale of the real mesh, it will probably be OK.

That answers what I was wondering about. Thank you. :-)

Most UV mapping apps and modelling programs that do UV mapping can generate UV coordinates outside of [0, 1].
Poser will read these and makes them available in the material room which is useful for some procedural materials.

Quote - Most UV mapping apps and modelling programs that do UV mapping can generate UV coordinates outside of [0, 1].
Poser will read these and makes them available in the material room which is useful for some procedural materials.

Yeah, I'm concerned mostly about models I want to use in Lightwave, ZBrush and Poser. LightWave and Poser obviously both can handle OBJ files with overlapping UVs since they treat materials separately, but ZBrush has fits over the idea. So if I want to model stuff that I can use in all apps, I need to either settle for some materials having very small relative spaces in the UV map, or use multiple regions.
Being able to use multiple regions is a much better answer, IMO, because then I can have parts taking up an entire UV "square" and not have to use ridiculously huge image maps to get good detail into them.