Originally Posted by Slewis
For the last time, Developer Builds are not Beta Builds.
You like saying that, don't you? Do you know what betas are? Just because Apple doesn't call
them betas, doesn't mean that they are not.
It works like this: OS X is in a continual state of development. Moving to major new versions, with several major new features and significant "under the hood" changes unsurprisingly brings with it lots of bugs, some of them serious. So you can't just realease that to the public. The OS is continually worked on, and the OS recompiled often. Each new recompile is given a number that is sequentially higher than the previous build.
The numbering system is made up of three parts: a number, a letter, and then another number. Each part works as follows:
The first number: represents major milestones. Panther was 7, Tiger is 8 and Leopard is 9.
The letter: major new versions (i.e. an increment of the first number) start at "A" and this is incremented when significant, but not major changes are made - e.g. they always increment from one 10.x.x to 10.x.x+1 movement (e.g. 10.4.1 was build 8B15, and 10.4.2 was 8C46), and sometimes increment in-between those releases never to see the light of day. This happened with the 10.4.8 to 10.4.9 move - PPC 10.4.8 was build 8L127, PPC 10.4.9 is build 8P135 - M, N and O were all internal.
The second number: represents the number of times that version has been built. No functional changes are made between these builds, it's all about squashing bugs. Any functional changes will result in the letter being incremented. e.g. build 8L started at 8L1, and had that had no problems, would have been released. However, various bits of code had to be corrected, then the OS rebuilt, then everything tested. With 8L, this process happened 126 times to result in 8L127, which was released to the public. Some intermediate builds between 8L1 and 8L127 were released to developers.
Now, what is the point of me saying all this? It is that, whether you like it or not, and whether Apple calls them such or not, any build numbered above a previous release, and below the next release, is a beta. Changes are made from the last release, and these are tested. Most are tested internal to Apple, some are also released to developers to test. Apple uses feedback from internal testing and from developers to determine whether the latest build is ready for release or not. If it is not, corrections (as opposed to functional changes) are made to the code to correct bugs, and a new build with higher "third number" results.
This is definitely what happens when there is a single development train. The question is what about those "top secret features"? Those are presumably being worked on separately, but one has to expect that the foundation of builds with "top secret features" are the builds also being released to developers. i.e., all the problems that we see in developer builds also exist in builds with "top secret features". Presumably, the "top secret features" builds have additional bugs associated with said features.