The publisher of an edition retains copyright in the form of the edition (e.g. typographical arrangement and layout) for 25 years after publication. When an edition of work that is out of copyright is published, the content of the work remains out of copyright, only the form is protected.
The copyright status tool uses the following coding to determine whether there is a published date as well as a copyright date:
008 field character position 6 contains 'p' or 'r' AND there is a date in 008 character positions 7-11 (those positions are not blank or 'u')
If the catalogue record matches this rule, the date in character positions 7-11 of the 008 field is used as the date the edition was published.