0 - 2 of 2 tags for udt

Hello,

In this case:

CREATE TABLE t1 (geom ST_GEOMETRY, id PRIMARY KEY not null integer) ;
CREATE TABLE t2 (geom ST_GEOMETRY, id PRIMARY KEY not null integer) ;

CREATE TRIGGER t_ins AFTER INSERT ON t
REFERENCING NEW TABLE AS nt
FOR EACH STATEMENT
BEGIN ATOMIC (
INSERT INTO t2 SELECT geom.ST_Envelope(), id FROM nt WHERE geom IS NOT null;
)
END;

INSERT INTO t (geom, id) VALUES (null,1);

I have the error : The owner expression of the UDM invocation 'ST_ENVELOPE' is not a UDT
What does it mean ?
Why ST_ENVELOPE is executed ?
And how to solve it ?

We can define a distinct UDT(User Defined Type) data type named "dollar" as:

CREATE TYPE dollar
AS DECIMAL(8,2)
FINAL;

What is the significance of the word "FINAL"?
Is it part of the syntax or we can define without using "FINAL" also.
Also , can anyone cite an example of a Structured UDT?How to define one?