write a new built in type

Hi all,
I with to write a new builtin type, I seen that what I have to do is:

1) ad on pgsql/src/include/utils/builtins.h     the signature for my function that will manipulate my     type

2) ad on pgsql/src/backend/utils/adt     a new file   my_type.c   with the implementation of all function inserted in
thefile   at point 1
 

and what else ? For example how may I define the name for my new type ?




Regards
Gaetano Mendola