decrementing number tags

[Orly Zimmerman]

Hi All,
Any ideas about how to get numbering tags such that the numbers decrement 
instead of increment?
I tried to use a number property of  <n-> or <n=N-1> - after setting the first 
in the series to 31
I need this because I want to create a table column with numbers starting from 
31 going down to 0 to describe error messages.
Any ideas will be appreciated.
Thanks,
Orly