From Hymnary Wiki
It is often the case that some hymns in a hymnal are copyrighted and others are not. The Copyrighted field indicates that this hymn is copyrighted. It is currently used to prevent the display of a page image of a copyrighted hymn.
- When there are copyrighted page images for a hymnal, this field must be set to '1' for copyrighted hymns. Otherwise, Hymnary.org will be violating copyright law.
- This field can also be set by the web page that connects page images to hymns, and that may be an easier and surer way of setting it than putting 1s into a spreadsheet.