There is zero documentation on what kind of spreadsheet functionality
works in XWiki tables. The only documented thing is SUM and it is
also the only thing I can get to work. Even simple things like
=(Address - Address) makes XWiki throw an exception on render.
Is there documentation somewhere that explains what can be done in
tables? Or is SUM about the, um, sum of it? I just wanted to have
one cell subtracted from another cell... is this possible?