Troubleshooting Failed Migrations

Thanks very much for this article and this series.  It's a doozy!  It actually is saving me right now, particularly Set-MoveRequest -MoveOptions @{Add='SkipFolderRestrictions'}.

I'd like to ask - what exactly are FolderRestrictions anyway.  When I look at them, in the DataContext of my final Failures entry, I can see there are entries for Admins, Delegate, and Owner, similar to audit log user types.  Would be nice to know what all I'm doing away with on the user's behalf when I skip these to get the mailbox offboarded.

EDIT:  I've found my answer I believe, from the following source: https://techevangs.com/tech-news-update/microsoft-exchange/troubleshooting-failed-migrations/ which looks like the original post of this post.  It is said there, that FolderRestrictions are the search criteria of a search folder (or at least that is how I've understood it).  In case I've got it wrong, please do fill me in.  Thanks again.