Base SDK 3.0 to SDK 4.0

Question

I installed SDK 4.0 and found that I lost access to all previous SDK versions prior to 3.2.

I have found a link to download SDK 3.1.3 so I have both .dmg install fil

Answer 1

The deployment target can be set to anything (even 2.2), but the Base SDK has nothing except 3.2 and 4.0. I would have thought if you set the deployment target to 3.0 for example, that the Base SDK could also be set to 3.0.

So if the deployment SDK is 3.0, and the base SDK is 4.0, which one is being compiled for?
Note in the new SDK, you can't select anything other than 3.2 and 4.0 as mentioned above.