SELECT template_type_code FROM Templates EXCEPT SELECT template_type_code FROM Templates AS T1 JOIN Documents AS T2 ON T1.template_id  =  T2.template_id
Show all template type codes that are not used by any document.
SELECT template_type_code FROM Templates EXCEPT SELECT template_type_code FROM Templates AS T1 JOIN Documents AS T2 ON T1.template_id = T2.template_id
select template_type_code from templates except select template_type_code from templates as t1 join documents as t2 on t1 . template_id = t2 . template_id
Show all template type codes that are not used by any document .