Accessing schema data in information schema

I'm updating the information schema for SQL:2003.  I'm having some 
difficulties with the "sequences" view.  It should look approximately 
like this (uninteresting stuff omitted):

CREATE VIEW sequences AS SELECT CAST(current_database() AS sql_identifier) AS sequence_catalog,        CAST(nc.nspname
ASsql_identifier) AS sequence_schema,        CAST(c.relname AS sql_identifier) AS sequence_name,        CAST(null AS
cardinal_number)AS maximum_value, -- FIXME        CAST(null AS cardinal_number) AS minimum_value, -- FIXME
CAST(nullAS cardinal_number) AS increment,     -- FIXME        CAST(null AS character_data) AS cycle_option    -- FIXME
FROMpg_namespace nc, pg_class c WHERE c.relnamespace = nc.oid       AND c.relkind = 's';
 

How does one get at the missing fields.  The only way I know is 
selecting from the sequence, but how does one work this into this 
query?  Somehow it seems that these things should be stored in a real 
system catalog.

Ideas (short of using PERFORM in PL/pgSQL)?

-- 
Peter Eisentraut
http://developer.postgresql.org/~petere/