Some published files, e.g. PDF's, should not be available to un-authenticated visitors. The most common class of restriction is for "Premium" content for Chorus America Members. A more-limited case is for Board Member "private" files.

Mar 2019 - Ed Stawick:

We only use "private" files three or four times a year for Chorus America board meeting materials.  Everything else should be public and marked  "premium"  is it is member-only content.

Private Files

Private Files When a file is uploaded to a file-upload content field, a content creator may select the upload "destination" of either public or private. "Private" in drupal means that the file will be stored in a location that is not directly accessible in the same way that a public file in /sites..…

What is a Project Lab Feature Context?