Thanks for the detailed response, but if I understand what you did the reason iTunes found the songs is not the reason you describe.
I think we agree on this but just to be clear; iTunes stores all new songs in the "music folder" that is established in preferences-advanced-general. By new music I mean music that is ripped by iTunes at the time that folder is in use or a song already ripped and added by dragging and dropping or importing when you have this checked "Copy files to iTunes Music folder when adding to library." If you don't have it checked it will point to to the song location but not copy it into the music folder.
Since you have it checked your songs went into this music folder.
You said "Launching iTunes with the option key depressed allowed me to create a new "iTunes LIBRARY" on Drive A."
Doing so puts the library files on Drive A but does not put the music folder on Drive A unless you go into preferences and change the location to a folder on Drive A. I did not see where you did this.
It does not automatically create a new music folder when you create a new library. The music folder never changes unless you change it in preferences, and if you do it changes it for every library on your computer. That goes for all preferences. They do not apply to just the library in use at the time you change them because there is only one set of preferences and they apply to any library launched by that copy of iTunes.
If I go to preferences in my main library my music folder is currently MusicFour/aug2/
If I launch iTunes with the option key down and create a new library on the drive MusicOne and look at preferences the itunes music folder is still Music4/Aug2. Any new song will be stored in MusicFour/Aug2 and the data stored in the library points to that song on MusicFour/Aug2. Therefore I can move the library files wherever I want because if I launch that library from any location it still points to the song on MusicFour/Aug2
It sounds like this is what you did. To find out do a "get info" on a song in your new library copy on drive B. I bet the song isn't actually stored on Drive B and that is why you can move the library around without losing track of the songs.
BTW your warning to always leave the copy box checked is fine if you have a small library but will not work if your library is too big to hold on a single drive.
Your concept of "relative names" is also off base.
Computers aren't clever enough to go out and find files unless you tell them the exact path. If you move the file from A to B and the pointer says it is in A there is no way it will find it in B.
.
I think we agree on this but just to be clear; iTunes stores all new songs in the "music folder" that is established in preferences-advanced-general. By new music I mean music that is ripped by iTunes at the time that folder is in use or a song already ripped and added by dragging and dropping or importing when you have this checked "Copy files to iTunes Music folder when adding to library." If you don't have it checked it will point to to the song location but not copy it into the music folder.
Since you have it checked your songs went into this music folder.
You said "Launching iTunes with the option key depressed allowed me to create a new "iTunes LIBRARY" on Drive A."
Doing so puts the library files on Drive A but does not put the music folder on Drive A unless you go into preferences and change the location to a folder on Drive A. I did not see where you did this.
It does not automatically create a new music folder when you create a new library. The music folder never changes unless you change it in preferences, and if you do it changes it for every library on your computer. That goes for all preferences. They do not apply to just the library in use at the time you change them because there is only one set of preferences and they apply to any library launched by that copy of iTunes.
If I go to preferences in my main library my music folder is currently MusicFour/aug2/
If I launch iTunes with the option key down and create a new library on the drive MusicOne and look at preferences the itunes music folder is still Music4/Aug2. Any new song will be stored in MusicFour/Aug2 and the data stored in the library points to that song on MusicFour/Aug2. Therefore I can move the library files wherever I want because if I launch that library from any location it still points to the song on MusicFour/Aug2
It sounds like this is what you did. To find out do a "get info" on a song in your new library copy on drive B. I bet the song isn't actually stored on Drive B and that is why you can move the library around without losing track of the songs.
BTW your warning to always leave the copy box checked is fine if you have a small library but will not work if your library is too big to hold on a single drive.
Your concept of "relative names" is also off base.
The reason I did NOT run into the problems you predicted is that although the absolute names of the files on Drive B were different (they were, after all, on Drive B), the relative names were not: everything other than "Drive B" was identical, so iTunes didn't really care.
Computers aren't clever enough to go out and find files unless you tell them the exact path. If you move the file from A to B and the pointer says it is in A there is no way it will find it in B.
.