What minor things can be included and not invalidate a copyright?
Scientific and critical editions can be protected by copyright as works of authorship if enough creativity/originality is provided. The mere addition of a word, or substitution of a term with another one believed to be more correct, usually does not achieve such level of originality/creativity. All the notes accounting for the analysis and why and how such changes have been made represent a different work autonomously copyrightable if the other requirements are satisfied. In the European Union critical and scientific editions may be protected also by the relevant neighboring right that protects critical and scientific publications of public domain works as made possible by art. 5 of the Copyright Term Directive. Not all EU member States have transposed art. 5 into national law.