RFC: Query Planner making a distinction between Cross Database and Cross Schema ?

Hey there everyone.
Sorry for what seems to be a rather strange
thought but, could we change the seperator used to
distinguish 'cross-database' vs 'cross-schema' ?
For example, i would expect the following
to work:
CREATE OR REPLACE FUNCTION test_autohist() RETURNS triggerAS 'BEGIN           INSERT INTO history.test2 VALUES
(new.field1,history.test_hist.nextval(),new.field2, new.field3, new.field4, new.creation_id, new.creation_date,
new.creation_id,new.creation_date);           RETURN ;           END;' LANGUAGE 'plpgsql';CREATE TRIGGER
test_autohist_trigAFTERINSERT OR UPDATE ON testFOR EACH ROWEXECUTE PROCEDURE test_autohist();
 

However, when i try it, as far as i can tell,
the planner parses it down, finds that the schema isnt
in the current 'search_path' and thus thinks its a cross
database call.
I understand that it may take the planner a 
while to go through all the available schema's to then
deduce that it isnt infact a schema at all and return
the fact that 'cross-database queries are currently not
implemented', therefore, in the realm of crazy idea, 
would it be possible to change the notation to reference
another db ?
I was thinking something along the lines of '@',
but i guess any other non-important ascii character would
make sense.
That way, the planner could decide wether or not
to attempt a schema resolution (history.table1) or database
resolution (live@table4).
Please note, i am not asking for any sort of 
'make cross-database work', merely asking if some sort
of 'clarification' between cross-database and cross-schema
would be beneficial. 
Ideas ? Comments ? 
regardsStef