[texhax] Corners

[Michael Barr]

My journal is reprinting a forty year old paper that has a construction 
that consists of a string (usually of one two characters) surrounded by 
corners.  You get something like what I want from \ulcorner#1\urcorner 
(these are from an AMS symbol font).  However that construction produces 
ugly looking spaces between the corners and their argument.  I would like 
to raise the corners, move them over, then add some extra space around the 
whole construction.  One complication is that they will have to put in 
boxes to raise them, which means that they won't know if they are in a 
sub/superscript or not.  I could kludge something together using 
\mathchoice, but it will ugly.  Is there a better way of doing this, or 
has someone already done it?

Michael Barr