Thanks… I see that’s the NT Design Workbook that shipped as part of the WRK.

Interestingly it does mention 32-bit OS/2 API support (Dos32* APIs). I’m not sure if this was just a plan never implemented or if they did implement it but pulled it out before shipping NT 3.1.

I now realise Microsoft did ship a beta SDK for OS/2 2.0 - but the last Microsoft pre-release of OS/2 2.0 is missing a lot of stuff compared to the final IBM OS/2 release - most notably the Workplace Shell (WPS). IBM originally planned to ship WPS as part of OfficeVision for OS/2 and only moved it into the core OS/2 product rather late in the 2.0 development cycle.