You can make synthetic HDR images: A composited three pass render at 3 different exposure levels; low, middle, high.
You gain radiance (dynamic range) from the different exposure levels. That's what an HDR image is, a radiance file. Any .jpg skydome can be turned into a .hdr skydome w/ radiant properties. That's a really nice feature to have. You don't have to use HDRShop, which is strictly non-commercial use only, for the compositing.
I don't know if that is what they mean; but some other 3d softwares can do that, so...

Sure, purists are everywhere and demand that photographic composites are the only 'true' hdris; but there is no fundamental difference between a shader/material based hdri and a photographically based hdri, in terms of the dynamic range that the file format can carry.
The photograph will probably look more realistic, but that isn't always the goal; and if Poser can composite/manufacture real radiance files, then there is nothing stopping anyone that owns it from using their own photographs to make photographic hdris either.

I doubt if it would be probe format, probably longlat. You need a camera lens shader for that (wraparound, panorama, whatever you want to call it). The render is done at 2:1 aspect and the lens shader warps the output so it is a seamless sphere map that can be used for environmental spheres and to drive the IBL.

Friends don't let friends use booleans.