Updated December 3, 2009. 

The Quest Error Manager (QEM) is a framework that will help you standardize the management of errors in a PL/SQL-based application.  With QEM, you can register, raise and report on errors through an API that makes it easy for all developers to perform error management in the same way, with a minimum amount of effort. Error information is logged into the instance (general information about the error) and context (application-specific name-value pairs) tables. You should install QEM separately for each application you build. QEM also offers programs that: substitute for DBMS_OUTPUT.PUT_LINE; trace execution of your application; and assert or validate assumptions.

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