Hi:
Don't you have the original file that created these document-level elements?
It will not be easy to do what you want. Assuming you used SAS to create the XLSX file in the first place, you need to read the CORE.XML file that is in the docProps folder of the XLSX archive (since an XLSX file is not one file, but is a collection of compressed files), as shown below:
Once you get to the CORE.XML file, then you'll need to read/parse it with SAS.
Cynthia