In[564]:= FromDigits["IM", "Roman"] During evaluation of In[564]:= FromDigits::nrom: The expression IM is not a proper string of roman digits. >> Out[564]= 999 Most developers would lazily deem the impropriety a fatal error to simplify their coding. Now watch them get sued: "I lost millions on a programmed trade when Mathematica turned my typo into a ridiculous date instead of aborting the transaction." --rwg