The “Universal Interfaces 1.0” interfaces are the original universal interfaces that were released on the “Macintosh on RISC SDK”. They had no version number when released, but have now been retroactively versioned “1.0”. Included in the folder are aliases to other interface files not released with the base set (e.g. ColorSync, AppleEvents, etc.). These other interface files may or may not be universalized.
Universal Interfaces 2.0a3
The “Universal Interfaces 2.0a3” contain 2.0a3 interfaces. They were released on ETO #16, MPW Prerelease. The 2.0 release is the beginning of a new release strategy. Instead of each project team at Apple distributing interface files with their own SDK, the project teams will roll their interface files into the next 2.0 release suite. For developers, this will mean one-stop-shopping for interface files. As you can see, most of the “Other” interface files in 1.0 have been rolled into the 2.0a3 release.
Please see “MPW Release Notes” section “Toolbox Libraries & Interfaces” for more details on specific changes.
