Creating a new type

Hi all,

I have to create a new composed data type to use in almost all tables of
my database. Something like:

CREATE TYPE time_interval (

Tbegin date,

Tend date

)

And when use this new type in my tables! So, I have to be able to get the
table_name or table_id that the type is in. For exemple:

CREATE TABLE employee (

Emp_id int,

Emp_name varchar(30),

Emp_time time_interval

)

So, when I execute an INSERT operation on this table, the functions that
deals with this type need the id or name of the table that the data was
inserted!

How can I get this ID or NAME inside this functions???

Thanks!!!