I found this in the docs:

• From the server, users can:
  • Run, filter and modify reports.
  • Export to a variety of formats.
  • Schedule reports to be distributed via email or FTP.

https://docs.intersystems.com/components/csp/docbook/DocBook.UI.Page.cls...

And docs on the API:
https://reportkbase.logianalytics.com/v23.1/api/index.html

Have you looked at the Zen demos in the SAMPLE namespace?
https://docs.intersystems.com/ens201817/csp/docbook/DocBook.UI.Page.cls?...

This demo page shows a file upload control:
http://<HOST>:PORT/csp/samples/ZENDemo.ControlTest.cls

One quick/dirty(?) way is to do a "View Code in Namespace" for "%SYS". Under the %SYS namespace the percent classes are not filtered out.