Trying to understand pdf import behavior

Hey there, I’m new to RemNote and so far very impressed. However, I don’t understand the behaviour when importing PDFs. At first it didn’t name the PDF after its file name but with something resembling a random string of letters and numbers. I figured out that my file didn’t have a title and that RemNote seems to use the title from the metadata of the PDF to name it. So I edited the metadata and my PDF at least had the right name.

But importing a PDF also generates this Top-Level rem which just has a title and is empty otherwise:

I can delete this Top-Level Rem and everything is still working, so I have a hard time figuring out what it is and what it does.

I just saw that it actually opens my PDF when I click on the link, still, I have absolutely no idea what it is exactly.