On Thu, Nov 4, 2010 at 5:40 PM, Mike Cargal <mike / cargal.net> wrote:
> /^(A(?!.*A)|B(?!.*B)|C(?!.*C)|D(?!.*D.*D)|DD(?!.*D))+$/

Mike, I think you deserve a prize.

-- 
Kendall Gifford
zettabyte / gmail.com