I. while declaring multiple <exception-type> in DD do we need to take care for superclass-subclass relationship as we did in catch block...catching subclass exception first....or in any sequence we can define them in DD,and it will take care of more specific first ...
II. say for an Error code "ABC" exception type is "ABCException" then either we can define <error-code> or <exception-type> ..not both..plz confirm.
I don't think the sequence like try-catch block is required in DD.
About your second question, I do not understand the reletionship beetween the Error code and Exceptions. The Error codes are HTTp Response specific and Exceptions are Java specific. For Some uncaught Exceptions The Server May throws 500 (Internal Server Error) code.
What HFSJ means by "cannot use exception-type and error-code together" is that for one error-page block, you must have : 1. Either an exception-type or an error-code element 2. a location element pointing to the error page to use.
But you can define multiple error-page blocks in your DD