I don't think this is something that you would have access to, the carrier would have done it in liteblue and only that carrier and HR would have access to that information.
<a href="https://liteblue.usps.gov/humanresources/applications/eRetreatRights/pdf/FAQs_RetreatRights_06072012_v8_WO.pdf">https://liteblue.usps.gov/humanresources/applications/eRetreatRights/pdf/FAQs_RetreatRights_06072012_v8_WO.pdf</a>
EDIT:
"How do I request retreat rights? City letter carrier craft employees (full time, part-time regular, or part-time flexible) who are involuntarily reassigned may submit a written request at the time of reassignment to be returned to the first residual vacancy in the level and craft in the installation from which reassigned. Clerk craft employees may submit a request to retreat to initial vacancies in their former pay level and to residual vacancies in higher/lower pay levels. However, the preferred method of accepting retreat rights is to use eJob Bidding in the Employee Apps - Quick Links on LiteBlue (https://liteblue.usps.gov). "
... To me that sounds like the note on the case also is a proper request