File Upload to a Panel via panel editor

When a file is uploaded to a panel using the panel editor ipart in the iMIS interface, where does the file name and type get stored so that when the file is downloaded from the panel, it is properly named? I see this function, _f73fe3f477f943d69469ec5bc80a6575_DownloadFileClick('E5B263FE1073325A05201EC460C7E7ED'), as the onclick event for the download button in the panel. I imagine that E5B263FE1073325A05201EC460C7E7ED is a GUID with the hyphens removed. I searched for this in the document business object but did not find it.

Thanks,
Korey