What is Tatkal Waiting List ('CKWL') in Railway's?

CKWL means that it is a waiting list under TATKAL. The difference between normal waiting list and CKWL is that when the normal waiting list moves up it goes to RAC category whereas CKWL means when the waiting list moves up you can expect confirmed berth.Hence the difference

Tatkal reservations come out of a Tatkal Quota (code 'CK', with waiting list 'CKWL')