While I have no formal expertise here, I always assumed that ® should appear on the baseline, as should ©. In fact I recall instances of seeing them used in close proximity, i.e. ©®. To have one be a superscript and one a baseline character would look ridiculous... except that I now find that a couple of the fonts on my system do just that. This differs from ™, which, having no enclosure, must be somehow distinguished from TM in regular text. The inconsistency, now that I'm aware of it, bothers me also. However, I feel the baseline glyph is the correct rendering and should prevail.
Sławomir Osipiuk
