[vessenes]

This is my point, exactly. A backup to a private DropBox folder of the iso is clearly fine even by Apple's own terms, regardless of what the law says.

However, a backup to a public Dropbox folder with a known, distributed link is.

So far so good. The question is, does DMCA require both to be taken down for a given notice, because they hash to the same file in the Dropbox database?

[trotsky]

Copy #1: the installed version of the OS (permitted)

Copy #2 (backup): The .iso file in your local dropbox folder (permitted if on the same computer as #1)

Copy #3: The .iso file on dropbox's primary storage array (not permitted - second backup copy)

Copy #4: The .iso file on dropbox's high availability storage array (not permitted - third backup copy)

Copy #5: The .iso file as copied to any other of your subscribed dropbox clients (not permitted - forth backup copy)

Not to mention the fact that copies #3 and #4 seem to obviously qualify as "available over a network where it could be used by multiple computers at the same time"

While I understand that there may be some difference in interpretation about these clauses I think you should reconsider your working definition of the term "clearly".

[fluidcruft]

> "available over a network where it could be used by multiple computers at the same time"

To me, they're clearly describing a network boot setup. i.e. you only have one installed copy of the OS, and you have a bunch of (possibly diskless) client machines boot from that single copy via netboot or similar.

[nitrogen]

To me, they're clearly describing a network boot setup.

Both "to me" and "clearly" will get you into serious trouble when dealing with legal matters. The likely outcome is that, if Apple decided to file a civil suit, or a prosecutor found grounds for criminal copyright infringement prosecution, the prosecuting attorneys would use whatever interpretation is in their favor.

[fluidcruft]

I don't see how "used by multiple computers at the same time" makes any sense in your interpretation but I was trying to be diplomatic.

[nitrogen]

"Used" is a word with a very broad definition. It doesn't just mean "run as primary operating system," it could also mean "capable of reading any of the bits of," or "looked at metadata of." The interpretation of "at the same time" is also rather flexible.

I'm not saying Apple will hunt you down and sue you (to paraphrase Jon Stewart). I'm saying, unless you're a lawyer, and you have another lawyer representing you, it's best for us non-lawyers not to think we understand legalese.

[fluidcruft]

I guess what you're saying is that nobody should use MacOS/iOS under any circumstances except after seeking the advice of an attorney.