postgres cust types

Hi ,
i created type on postgres
CREATE TYPE order_list AS (order_id bigint);
it works fine.

then, i try to create a other table type using above created type.
like,
--create or replace type suborder_list_table as table of suborder_list;
this on *oracle *formate

i need to convert *postgres *and how to create a table type in postgres is
it possible
or
else any other method.

FYI,i am using these types in a function.

thanks in advance,