In addition to his question, I would like to ask some more general questions regarding copyright editors and publishers.The score is published by Kalmus under the Kalmus classic edition series. I'm sure it is a reprint of the Boosey and Hawkes score because of the engraving and layout (cf. Haydn symphonies published by Boosey in Variations Project). Since Kalmus reprinted it, I assume it is PD. Furthermore, at the bottom of the first page, the name "Belwin Mills" is printed.
However, I have a few concerns. The fact that Kalmus reprinted it makes the score PD in the US. But what about Canada? If rules pertaining to time of composer's death, then it is PD in Canada. But what about the editor? I'm sure an edition by Boosey has to be edited by someone, and I think the original Boosey edition is published in the 40s or 50s. Since it does not say in the edition, we have no idea who the editor is and when is their time of death. If they died less than 50 years ago, will this affect the PDness of the score in Canada? I somehow feel despite being reprinted by Kalmus, we should thread carefully less the editor comes out of the blue and challenge IMSLP. I really do not want that to happen.
1. Do publishers have copyright *at all* by themselves? Or is it copyrighted purely through the editor/composer's copyright?
2. Is a significant editor (as in, significant enough to warrant copyright protection) usually (as in, near 100%) identified on the score? Are most scores without identified editors that way because the editing is too insignificant, or do some publishers just like to hide editor names?
3. Is there a precedent (in any country) for the claiming of public domainness on a publication without identified editor, but with significant editing, on the grounds that the editor is unidentified (not publicly known)? I ask this because I'm not sure what constitutes "public knowledge", though I know there is such a clause in Canadian copyright law, which grants only a publication+50 copyright to unidentified authors.