forwarding question?

When are messages implicitly stored in $DEFAULT?

In the below

 :0
          * ^From.*peter
          * ^Subject:.*compilers
          {
             :0 c
             ! william(_at_)somewhere(_dot_)edu

             :0
             petcompil
          }

If I remove :0 
                petcompil

does the message get forwarded _and_ stored in $DEFAULT?

If not, how does one set a rule up to forward and store in $DEFAULT?

do I have to explicitly put it in default with :0 $DEFAULT?