The complete SDK for OS4 is probably better than SDK for MOS. This because OS4 team can take advantage of older NDK revisions and simply paste new API calls to the docs. Not to mention all legacy SDKs from OS 1.x/2.x times and RKRMs in AmigaGuide format (and AmigaMail archives etc... they simply have good base compilation to work on).
MOS SDK provides autodocs for MUI 3.9 though. It is worth of reading for all MUI fans out there.
