[CentOS] shadow file question

Feizhou wrote:

> There is this * in the password field of the shadow file for certain 
> accounts.
>
> I know that the ! is to indicate a locked account but what does a * mean?
>
My understanding is that anything in that field that is not a valid 
encrypted password means the account is disabled.  I believe that '!!' 
and '*' are simply 2 different conventions indicating the same thing.

-Steve