Inconsistent file permissions in iTunes library

Thanks for your help, turingtest2. I found the documents linked interesting but, as with the suggestions from jeremy_v, I don't think they have made me understand why the difference in permissions is there. I have added a few more comments in my reply to jeremy_v but it all remains mysterious to me.

Thanks for your help. I found the linked document interesting but don't feel I have made progress in understanding why some entries in the library show 'Read & Write' for all known users while many others only have 'Read only' permission.

I probably should have mentioned that my iTunes library is on an external NAS. I'm not clear whether that is part of the original problem but maybe it is the reason why Get Info displays don't show any lock icon.

All the "top level" entries in the Library have 'Read & Write' permission...

But when I try to use 'Apply to enclosed items', the command appears to be accepted but permissions are not changed in the 'enclosed items'. Puzzles me too.

Thanks again. I too rather suspect that the NAS is involved somehow. The stackexchange link was interesting and there were one or two things mentioned there that I might follow up.

What I still haven't understood is how some entries have 'Read & Write' permissions while others are 'Read only'. One possibility is that I had to replace the NAS at one stage and maybe the two NAS's from different manufacturers work differently. That would at least be an explanation but I haven't been able to convince myself yet that it is the case (largely because I haven't recognised any logical pattern in the affected files, e.g. from their dates).

I'll report again if I ever find a convincing solution. At the moment it isn't too great a problem for me, since I found the work-around of changing the permissions manually. After that I was able to add the problem discs to the iTunes library.