create or replace type TYPETEST as object(
abc varchar2(20)
);

create or replace type typetest1 is table of TYPETEST;

create or replace function fnTestType return typetest1
is
Result typetest1 := typetest1();
begin
Result := typetest1();
Result.extend;
Result(Result.count) := TYPETEST(NULL);
Result(Result.count).abc := 1;

Result.extend;
Result(Result.count) := TYPETEST(NULL);
Result(Result.count).abc := 2;

return(Result);
end fnTestType;

select * from table(cast(fnTestType as typetest1));

drop function fnTestType;
drop type typetest1;
drop type TYPETEST;