this is a basic notification feature and has nothing to do with extended notification. basically, the MDG workflow will use the number of hours you enter to send a simple e-mail to the processors if they didn't complete their task. in general, it is recommended to use extended notifications instead of this. at the same time, you can build a more sophisticated e-mail notification following this document How To - Master Data Governance for Material: Send a Mail Notification During the Governance Process.
here is the text of the e-mail that is triggered by the EXP_COMPLETE_HOURS:
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Dear User,
You were assigned as processor of change request #CHANGE_REQUEST.CREQUEST#. It has expired. Please check your BRWF workflow tasks and proceed with this task.
For any problem, please contact system administrator.
Best Regards
SAP Workflow
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