Formats is a USER (custom) column.
You need to revisit what you did to make it. (or throw the column away)
Personally, I just look at Formats: in the details pane (or in the metadata editor)
RAR is a valid format for a multi-HTML file book, so you could really have all 3 formats
formats:rar is the search for those that (should) exist
If you have been
messing below the skirts, rum Library MAINTENANCE and get the DB back int shape (and quit messn' around
)
Select books: Right click: Remove Books: Remove a selected format
Use with care...
There is no easy undo