English to Chinese Other Human Resources

I understand that I have the right to revoke this authorization, in writing, at any time by sending such written notification to _______.
I also understand that my revocation is not effective to the extent that the persons I have authorized to use and/or disclose my protected health information have acted in reliance upon this authorization.
怎么理解这里的“acted in reliance upon ”呢？谢谢！