Comments
When one builds a profile programmatically, one can enter extensions and elements in any order. The generated XML appears to reflect that order. However, Lloyd mentioned that when building profiles, one must be sure to place extension elements first and then other elements in the same order they appear in the core resource. Doing so places a heavy burden on implementers. I would suggest that the reference implementation orders the attribute as they should be ordered without requiring the developer to order them as that order is already known.

Grahame's Comments
move the heavy burden to the RI then? Well, in theory that makes sense, and I'll see what I can do