My custom columns are general, so I just keep my Manuals in my main Library.
Except for Author and Title, I don't believe the Police will seek you out for leaving fields blank.
In case of Manuals: if the author is not specified, I use the Publisher there also (sometimes embellished

). eg LG Staff
I also tag the document: UG (users Guide), QSG (Quick Start Guide), IG (Installation Guide), Wnty ...
I even use 'Series' to tie a set together (LG BD [0])