composite data types

someone just point me to the 'composite data types'
documentation, please... (note that this is NOT inheritance):

-- first we roll-our-own datatypes:
    CREATE TABLE vol (
        high int4,
        wide int4,
        deep int4
    );
    CREATE TABLE changes (
        who int4,
        at  datetime
    );

--now we incorporate those composite types in a new table
    CREATE TABLE something (
        info varchar(30),
        munged changes, -- use the composite CHANGES type
        dimensions vol, -- use composite VOLume type
        other char(2)
    );

\d something
          Table "something"
 Attribute  |    Type     | Modifier
------------+-------------+----------
 info       | varchar(30) |
 munged     | changes     |
 dimensions | vol         |
 other      | char(2)     |

--here we try to utilize those composite gizmos-go-boom:
INSERT INTO something VALUES(
    'whatever',100,now(),36,24,36,'zx'
);
ERROR:  Attribute 'munged' is of type 'changes' but expression is of type 'int4'
    You will need to rewrite or cast the expression

INSERT INTO something VALUES(
    'whatever',(100,now()),(36,24,36),'zx'
);
ERROR:  parser: parse error at or near ","

INSERT INTO something (info,other) VALUES( 'whatever','zx');
INSERT 937857 1
-- this works, because we avoid the composite fields altogether.

INSERT INTO something.dimensions VALUES (36,24,36);
ERROR:  parser: parse error at or near "."

INSERT INTO something(dimensions) VALUES (36,24,36);
ERROR:  Attribute 'dimensions' is of type 'vol' but expression is of type 'int4'
    You will need to rewrite or cast the expression

update something set dimensions = (36,24,36);
ERROR:  parser: parse error at or near ";"

update something set dimensions = (36,24,36)::vol;
ERROR:  parser: parse error at or near "::"

select * from something;

   info   | munged | dimensions | other
----------+--------+------------+-------
 whatever |        |            | zx
(1 row)

so, HOW can you use a composite type? where's the doc?

--
It is always hazardous to ask "Why?" in science, but it is often
interesting to do so just the same.
        -- Isaac Asimov, 'The Genetic Code'

will@serensoft.com
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