[texhax] left-hand side superscript?

[Robin Fairbairns]

> On Thu, 5 Feb 2004 morten at s3.kth.se wrote:
> 
> > I wonder if there is any good way to obtain a superscript on the left-hand 
> > side of a variable in LaTeX.
> 
> Please check out the "\sideset" command available in the "amsmath" 
> package.

i thought that too.  so i tried it before posting: doesn't work for
left-subscripting _letters_ (what the op is after).  had i read the
documentation first (it's in amsldoc) i'ld have known -- it's for
("large") operators only.