Yes Gareth is correct. If you are dealing with SGML DTDs then you will need to create a separate Custom directory for each version since the DTDs are compiled. You can assign the DTDs automatically using the APTCUSTOM setting in your environmental variable. If you are using XML based DTDs then you do not have to compile them and you can access them with any version of the editor. We have separate directories fro 5.4, 6.0, 6.1, and 7.0 since we have not moved to 7.1 yet. Good luck.