Questions about using exceptions

Hi all, I've got two questions about using PEAR_Exceptions when building a PHP5 Pear class: 1.) When extending a PHP 4 class, should I throw an exception my own and work around the existing code? 2.) Should I only add a @throws note in the DocBlock for exceptions which are thrown in that particular function, or also exceptions thrown in other functions called by this function? Thanks for the advice. Best regards, Arnold Daniels Bean IT