How do I list the constraints of a DOMAIN? Consider the following scenario:

CREATE DOMAIN dom_zipcode AS text;
ALTER DOMAIN dom_zipcode
  ADD CONSTRAINT zipchk CHECK (char_length(VALUE) = 5);


Now, if I want to drop that constraint with ALTER DOMAIN, The manual says:

ALTER DOMAIN name
    DROP CONSTRAINT [ IF EXISTS ] constraint_name [ RESTRICT | CASCADE ]


But how can we find constraint_name? \dD only shows the constraint's definition (CHECK statement).

\dD dom_zipcode ;
                             List of domains
 Schema |    Name     | Type | Modifier |             Check
--------+-------------+------+----------+--------------------------------
 public | dom_zipcode | text |          | CHECK (char_length(VALUE) = 5)
(1 row)


I can dump the schema using pg_dump, but I believe there must exist a more elegant way to establish this using the psql terminal.
PostgreSQL's System Catalog

SELECT conname
FROM pg_constraint
WHERE contypid = 'dom_zipcode'::regtype;