Word 2007 Equations: How to stack symbols

"You can use \above and \below:

a=\above(""foo"") b

becomes

a=┴""foo"" b

which becomes

A more or less complete description of the formula language in Word is given in Unicode Technical Note #28, although the final implementation differs somewhat in some areas. Unfortunately this is the only real documentation that's there (I asked the author of the math typesetting stuff at MS :-))."